Oem Gutted DP vs Aftermarket Catless DP

[ssgm1x]

Will OEM Gutted Downpipes yield me the same benefits as purchasing an aftermarket Catless Downpipe ?
Will they flow the same? Or do aftermarket flow better?
I ask because I just picked up a set for cheap. I like that the Oem are double walled with Heat Shields and have Perfect fitment but am curious if these Oem Gutted will yield me the same benefits as aftermarket ones. Anyone have any experience running both ?

[fazalcon]

Originally Posted by ssgm1x

Will OEM Gutted Downpipes yield me the same benefits as purchasing an aftermarket Catless Downpipe ?
Will they flow the same? Or do aftermarket flow better?
I ask because I just picked up a set for cheap. I like that the Oem are double walled with Heat Shields and have Perfect fitment but am curious if these Oem Gutted will yield me the same benefits as aftermarket ones. Anyone have any experience running both ?

+1
Would also love to know the answer to this.

[M3 Pilot]

Originally Posted by ssgm1x

Will OEM Gutted Downpipes yield me the same benefits as purchasing an aftermarket Catless Downpipe ?
Will they flow the same? Or do aftermarket flow better?
I ask because I just picked up a set for cheap. I like that the Oem are double walled with Heat Shields and have Perfect fitment but am curious if these Oem Gutted will yield me the same benefits as aftermarket ones. Anyone have any experience running both ?

I first ran a VSRF downpipe then bought a set of stock DP and gutted it.

I couldn't tell the difference between both. The shape is different obviously. Stock cats are flatter in shape if you've seen it. Given that I'm on stock turbo, I don't think the gutted stock cats will be restrictive.

[idiot]

Originally Posted by M3 Pilot

I first ran a VSRF downpipe then bought a set of stock DP and gutted it.

I couldn't tell the difference between both. The shape is different obviously. Stock cats are flatter in shape if you've seen it. Given that I'm on stock turbo, I don't think the gutted stock cats will be restrictive.

Would you say the gutted stock has a big difference over unmodified stock? I'm thinking about just gutting my stock pipes too.

[M3 Pilot]

Originally Posted by idiot

Would you say the gutted stock has a big difference over unmodified stock? I'm thinking about just gutting my stock pipes too.

Noticeable difference, Yes.

I uninstalled the VSRF and drove around on my unmodified Stock DP while waiting for Stock DP to be gutted.

I'm usually not sensitive to power increments but I can feel revs are a bit lazy or slower from about 5000 rpm onwards on the unmodified Stock DP.

When on VSRF and unmodded Stock DP, my JB4 was on Map 2 so no changes there.

Just make sure your mechanic gut the cats as clean as possible so that the inside is smooth to reduce turbulence or restrictions.

Edit: I'm not sure if the cops in Sydney issue defects notice like they do in Perth. If the idea is to pass inspections, make sure you know the which way the DPs are facing before you mark out where you want to cut your DP. This is to ensure you don't cut the DP where the welds will be very visible should they want to put your car on a hoist to see.

[MR RIZK]

Originally Posted by M3 Pilot

Edit: I'm not sure if the cops in Sydney issue defects notice like they do in Perth. If the idea is to pass inspections, make sure you know the which way the DPs are facing before you mark out where you want to cut your DP. This is to ensure you don't cut the DP where the welds will be very visible should they want to put your car on a hoist to see.

The EPA use a heat probe so they can see a temperature change ie. cool pre cat > hot cat > cool post cat. This provides a quick check if the cat is functioning with a internal biscuit.

[MakeMuricaGreat]

Originally Posted by MR RIZK

The EPA use a heat probe so they can see a temperature change ie. cool pre cat > hot cat > cool post cat. This provides a quick check if the cat is functioning with a internal biscuit.

Depending upon the state, correct.

Some states utilize OBDII testing to confirm 'readiness' monitors are set at emissions inspections, whereas the more Nazi-esque states utilize sniffers and/or visual inspections to confirm the presence of cats.

[MR RIZK]

I should of been clearer. I have seen this in Sydney. Not sure about other states in AU

[MakeMuricaGreat]

Originally Posted by MR RIZK

I should of been clearer. I have seen this in Sydney. Not sure about other states in AU

Yeah, it's similar here in the United States where it varies on a state basis.

I've been trying to find out what it is on a state basis in Australia just for the sake of contributing to the thread, but it's so vague and there's not as many people trying to say "fuck off" to to catalytic converters down there as opposed to here!

[ssgm1x]

Luckily My car is not due for inspection for another 4 years since Car is New...