I have 2 solutions and need some input

GooDy151 · 03-21-2013, 01:42 PM

I have Z4 35i so I do not have so many options.
Down pipe is kinda expensive because they only have AR make it to fit e89.

Here is 2 solutions that I have.

1. keep the first cat , delete the second cats (straight pipe) , delete the mufflers. this option I don't really spend money much safe a lot of money.

2. get AR catless (non resonate) down pipe , delete secondary cats , keep the muffler or after market muffler. This option will cost me 3k plus.

So... my question is speaking about performance wise (flow and back pressure balh blah) not about sound,
Do you guy think it has a $3k different in the performance ?

How are these 2 solution has in term of flow and back pressure that engine needs.

BTW my car has:
FMIC , Charge pipe , DCI , High boost map on ProCede V5

thank you guys.

Marcadelic · 03-21-2013, 02:14 PM

deleting your secondary and mufflers will not give you any noticeable gains, it'll just make the car A LOT louder.

If you want to increase hp you definitely need to get catless dp's, but you have to justify if it's worth the money to you. 3k's a lot, it should be more like 1k total, leave the secondaries and delete the muffler if you want it loud.

georgelb · 03-21-2013, 02:36 PM

Yeah, $3k is about 3x too much; you can buy them straight from AR for a bit less than $1k.

2jzn54 · 03-21-2013, 03:03 PM

why not just cut out the cats on your stock DPs and call it a day?

Marcadelic · 03-21-2013, 03:07 PM

Quote:

Originally Posted by Daily Three

why not just cut out the cats on your stock DPs and call it a day?

ive never heard of anyone doing that on our cars

2jzn54 · 03-21-2013, 03:11 PM

Quote:

Originally Posted by Marcadelic

ive never heard of anyone doing that on our cars

a lot of people have.. i personally don't know many who have, but i do know someone who did it on their 135... to run more boost the main purpose of modifying the exhaust is to delete the restriction... the restriction is the cat.. delete it..

GooDy151 · 03-21-2013, 03:58 PM

Quote:

Originally Posted by georgelb

Yeah, $3k is about 3x too much; you can buy them straight from AR for a bit less than $1k.

I mean $900 for AR + $1500-$2500 for after mater exhaust (muffler)

GooDy151 · 03-21-2013, 04:04 PM

Quote:

Originally Posted by Daily Three

why not just cut out the cats on your stock DPs and call it a day?

It could be done but a little complicate to get in there for exhaust shop. Meaning labor will cost half of the price of AR.

2jzn54 · 03-21-2013, 04:08 PM

Quote:

Originally Posted by GooDy151

It could be done but a little complicate to get in there for exhaust shop. Meaning labor will cost half of the price of AR.

understandable, but your main concern is money right?... depending on the shop you could get it done reasonably cheap comparatively.. or if you have a buddy who is willing to do it for a small fee or some beers..

If you are paying more than 250 for labor on DPs you are getting ripped off.. I wouldn't even pay that..

2jzn54 · 03-21-2013, 04:12 PM

also your garage is disturbingly awesome

GooDy151 · 03-21-2013, 04:20 PM

Quote:

Originally Posted by Daily Three

understandable, but your main concern is money right?... depending on the shop you could get it done reasonably cheap comparatively.. or if you have a buddy who is willing to do it for a small fee or some beers..

If you are paying more than 250 for labor on DPs you are getting ripped off.. I wouldn't even pay that..

Well... my boy will do secondary cat and muffler delete for free.
but his worker look at the down pipe and the pull up alldata time to remove it and it was like 6hr on one of them and 2.5 on another on on my Z4.

And he didn't wanna do it his shop just do cat replacement for daily driver car.

Money is not super big issue if it worth the price.

If main cat has more restriction than secondary cat then I'll have to think about getting AR.

and thank you for comment on my garage

2jzn54 · 03-21-2013, 04:34 PM

if your main concern is being able to run more boost (based on the cars in your sig im assuming so) go with a catless DP and leave the rest alone for the time being.. Your buddy can always hack out the rest as you mentioned. muffler delete will likely be too loud, but if you are down with running straight pipes go for it.. my recommendation would be replacing the DPs with catless ones and gutting your secondary cats.

GooDy151 · 03-21-2013, 05:40 PM

Quote:

Originally Posted by Daily Three

if your main concern is being able to run more boost (based on the cars in your sig im assuming so) go with a catless DP and leave the rest alone for the time being.. Your buddy can always hack out the rest as you mentioned. muffler delete will likely be too loud, but if you are down with running straight pipes go for it.. my recommendation would be replacing the DPs with catless ones and gutting your secondary cats.

you say gutting secondary , is that mean cut and weld straight pipe on ?

psmitty95 · 03-21-2013, 05:50 PM

Quote:

Originally Posted by GooDy151

you say gutting secondary , is that mean cut and weld straight pipe on ?

I think that's what they mean. My car is at the shop right now getting secondary cats deleted. Cut it out and do straight pipe. I'll be VRSF catless DP's then secondary cat delete. Otherwise stock e90 exhaust with resonators

BAL278 · 03-21-2013, 06:43 PM

Yeah for performance.. Catless downpipes.. Merely deleting the cat from the stock down pipes will affect back pressure and will not perform as well as cat less downpipes..
You should have plenty of room for catless downpipes.. Maybe contact BMS or VRSF to see if you can use their dps.. Much cheaper than AR

Jeff@TopGearSolutions · 03-21-2013, 07:01 PM

The main cat is the biggest restriction and the biggest adder of power.

Why dont you just pull the stock downpipes and have your shop gut them? That's the least expensive route and the most HP gain.

bigdaddycane · 03-21-2013, 07:25 PM

Quote:

Originally Posted by Daily Three

why not just cut out the cats on your stock DPs and call it a day?

ghetto

OP, go with the AR DP....they make great pipes that fit well and make good power.

GooDy151 · 03-21-2013, 07:34 PM

Thanks for all input guys !! Cheers

2jzn54 · 03-21-2013, 10:46 PM

Quote:

Originally Posted by BAL278

Yeah for performance.. Catless downpipes.. Merely deleting the cat from the stock down pipes will affect back pressure and will not perform as well as cat less downpipes..
You should have plenty of room for catless downpipes.. Maybe contact BMS or VRSF to see if you can use their dps.. Much cheaper than AR

That doesn't make much sense... Removing the cat from the stock downpipes would relieve the car of back pressure. It makes it a catless downpipe.. The only difference with some of the aftermarket catless options are that they have a larger diameter.. These cars at an bolt on level don't really require the larger diameter pipes..

2jzn54 · 03-21-2013, 10:55 PM

Quote:

Originally Posted by bigdaddycane

ghetto

OP, go with the AR DP....they make great pipes that fit well and make good power.

Why is it ghetto because a vendor didn't market it to you?

Can you hear/see the difference if a car has an AR pipe vs a gutted stock dp?

...Which depending on where you live is getting murdered like everything else under your car daily or seasonally

Blue Streak · 03-22-2013, 12:03 AM

In regard to gutting your stock downpipes cats, you may want to consider how much a new set of OEM primary cats cost. You're going to need to install them again some day and if you have them in a box in your garage, it's going to be a lot cheaper than buying new ones again before selling your car or trying to pass a smog test if you've failed after the first try.

cstavaru · 03-22-2013, 05:14 AM

Quote:

Originally Posted by Marcadelic

ive never heard of anyone doing that on our cars

I did on mine

It's cheap and the power gains are the same. They just don't look very nice, but they work:

http://www.e90post.com/forums/showthread.php?t=451224

03-21-2013, 01:42 PM	#1
GooDy151 Private First Class 20 Rep 131 Posts Drives: BUS Join Date: Sep 2008 Location: SF iTrader: (0)	I have 2 solutions and need some input I have Z4 35i so I do not have so many options. Down pipe is kinda expensive because they only have AR make it to fit e89. Here is 2 solutions that I have. 1. keep the first cat , delete the second cats (straight pipe) , delete the mufflers. this option I don't really spend money much safe a lot of money. 2. get AR catless (non resonate) down pipe , delete secondary cats , keep the muffler or after market muffler. This option will cost me 3k plus. So... my question is speaking about performance wise (flow and back pressure balh blah) not about sound, Do you guy think it has a $3k different in the performance ? How are these 2 solution has in term of flow and back pressure that engine needs. BTW my car has: FMIC , Charge pipe , DCI , High boost map on ProCede V5 thank you guys. __________________ '09 Z4 35i on the way of build '06 997s built motor from Vision Motorsport 421WHP N/A '96 Skyline R33 GTS stock trying to register it. '99 Subaru Impreza 2.2 JE pistons , HKS rods , Jun cam 272 / 272, Greddy T78 32D , Sard 1000cc Inj., Tein and Tomei SQ trans , 10.21sec Last edited by GooDy151; 03-21-2013 at 02:02 PM..
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03-21-2013, 02:14 PM	#2
Marcadelic Instagram: @Marcadelic 243 Rep 2,697 Posts Drives: 335is Join Date: Jan 2010 Location: Tampa iTrader: (4)	deleting your secondary and mufflers will not give you any noticeable gains, it'll just make the car A LOT louder. If you want to increase hp you definitely need to get catless dp's, but you have to justify if it's worth the money to you. 3k's a lot, it should be more like 1k total, leave the secondaries and delete the muffler if you want it loud. __________________ \| New: 2018 F80 M3 \| Old: 335i / 335is \| Instagram: Marcadelic \|
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03-21-2013, 02:36 PM	#3
georgelb nsomneeak 39 Rep 501 Posts Drives: E92 RB 335i Join Date: Apr 2010 Location: DFW, TX iTrader: (3) Garage List 2007 335i [8.00]	Yeah, $3k is about 3x too much; you can buy them straight from AR for a bit less than $1k. __________________ RB Turbos w/ N20 TMAP Sensor \| 93 Octane Protune by Cobb Plano \| xHP Stage 3 \| BMS DCI \| STETT CP \| Forge DVs \| RB PCV \| Helix FMIC \| CP-E Catted DPs \| Walbro 450 \| Bilstein B12 \| M3 Control Arms \| Defiv Lockdown Kit \| BBS CH \| Michelin A/S 3+ Hixson BMW of Monroe, LA - Shady Dealer \|
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03-21-2013, 03:03 PM	#4
2jzn54 Captain 41 Rep 823 Posts Drives: 07 E90 335i 6MT Join Date: Jul 2011 Location: United States iTrader: (6)	why not just cut out the cats on your stock DPs and call it a day?
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03-21-2013, 04:12 PM	#10
2jzn54 Captain 41 Rep 823 Posts Drives: 07 E90 335i 6MT Join Date: Jul 2011 Location: United States iTrader: (6)	also your garage is disturbingly awesome
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03-21-2013, 04:34 PM	#12
2jzn54 Captain 41 Rep 823 Posts Drives: 07 E90 335i 6MT Join Date: Jul 2011 Location: United States iTrader: (6)	if your main concern is being able to run more boost (based on the cars in your sig im assuming so) go with a catless DP and leave the rest alone for the time being.. Your buddy can always hack out the rest as you mentioned. muffler delete will likely be too loud, but if you are down with running straight pipes go for it.. my recommendation would be replacing the DPs with catless ones and gutting your secondary cats.
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03-21-2013, 06:43 PM	#15
BAL278 Major 48 Rep 1,010 Posts Drives: E92 335xi JB Join Date: Jun 2011 Location: North NJ iTrader: (3)	Yeah for performance.. Catless downpipes.. Merely deleting the cat from the stock down pipes will affect back pressure and will not perform as well as cat less downpipes.. You should have plenty of room for catless downpipes.. Maybe contact BMS or VRSF to see if you can use their dps.. Much cheaper than AR __________________ 2008 335xi Jet Black//Coral Red VTT Stage 1+// Procede V5//VRSF DPs//AMS FMIC//KW V1//M3 Sways & Sub Bushings// Alpina AT flash Apex EC-7//Michelin PSS//Dinan CAI
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03-21-2013, 07:01 PM	#16
Jeff@TopGearSolutions 3441 Rep 79,211 Posts Drives: C6 Z06, 09 335i, 10 335xi Join Date: Dec 2008 Location: www.TopGearSolutions.com iTrader: (37)	The main cat is the biggest restriction and the biggest adder of power. Why dont you just pull the stock downpipes and have your shop gut them? That's the least expensive route and the most HP gain.
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03-21-2013, 07:34 PM	#18
GooDy151 Private First Class 20 Rep 131 Posts Drives: BUS Join Date: Sep 2008 Location: SF iTrader: (0)	Thanks for all input guys !! Cheers __________________ '09 Z4 35i on the way of build '06 997s built motor from Vision Motorsport 421WHP N/A '96 Skyline R33 GTS stock trying to register it. '99 Subaru Impreza 2.2 JE pistons , HKS rods , Jun cam 272 / 272, Greddy T78 32D , Sard 1000cc Inj., Tein and Tomei SQ trans , 10.21sec
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03-22-2013, 12:03 AM	#21
Blue Streak Gunny 30 Rep 623 Posts Drives: '07 E90 335i 6MT, 2016 F10 535 Join Date: Sep 2007 Location: San Diego, CA iTrader: (0) Garage List 2007 E90 335i [9.00]	In regard to gutting your stock downpipes cats, you may want to consider how much a new set of OEM primary cats cost. You're going to need to install them again some day and if you have them in a box in your garage, it's going to be a lot cheaper than buying new ones again before selling your car or trying to pass a smog test if you've failed after the first try. __________________ 2007 E90 335i 6MT, ZSP, Nav, PDC, CA, Montego Blue, Terra Dakota leather, CDV, clutch-stop, E46 M Shift Knob, Logic HVI, JB4 PnP, MS 3" downpipes, Koni Yellow adjustable sport shocks, RE 12mm(f)/BMS 15mm(r) spacers, Blacklines, LUX 5.0 LED halo ring lights, DAEOS (Vista) harness, GP Thunder 7500k fogs, 35% sides-20% rear tint, matt black kidney grill, matt black 335i trunk badge
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