[iranjha]

My '19 is currently Stage 1 (bootmod3) completely stock, and I've had zero issues with it or the tune and have been pleased with my experience.

It's now getting primary and secondary catless downpipes (mainly for the sound), but it will mean that I could flash it to bootmod's Stage 2 map and put down some serious power.

Just wondering if anyone has any longer term experiences on Stage 2 with how well a stock car with just downpipes handles the extra push, and if anyone specifically recommends just staying Stage 1 with the downpipes.

Have not seen a whole bunch of posts on here about catless downpipes or Stage 2, but I could just be searching wrong.

TIA!

[brad65ford]

Whats odd is I feel that state 2 might actually cause less stress on the motor/turbos since it can breath better. When you look at the power percentages BM3 states between their stages its really not a whole hell of a lot more. Stage 1 E30 is close to Stage 2 93 even.

[AngryInch]

Ya, I agree, catless IMO would be better long term. The engine can breathe, the exhaust gas temp will likely be lower with the increased flow and lack of cats stuffed right behind the turbos.

The main thing is not too much timing for the boost and good quality high octane fuel. Also if you live in a hot climate, it wouldn’t be driving the hell out of the car…

I will also be running catless downpipes with a tune for the entire time I own this vehicle.

[brad65ford]

I could be wrong but from what I read BM3 is pretty conservative when it comes to their F90 M5 tunes. I'm running stage 1 now and waiting for my DP to arrive, will be running their stage 2 software when it happens.

[iranjha]

Originally Posted by brad65ford

I could be wrong but from what I read BM3 is pretty conservative when it comes to their F90 M5 tunes. I'm running stage 1 now and waiting for my DP to arrive, will be running their stage 2 software when it happens.

We're in the same boat! I've heard the same. Nice to know people can confirm.

Thanks everyone. I expected best case scenario to be that running stage 2 with downpipes would be no issue at all. But the extra peace at mind knowing it might actually be healthier than stock with stage 1 is welcome!

[iranjha]

Also, does anyone have a simple answer to the pros and cons of primary and/or secondary catless downpipes? Trying to weigh whether I should do both or one and not the other.

I'm wondering in terms of smell and sound, in that order.

Ideally I want a setup that doesn't smell and sounds better than stock exhaust. Will I still be able to safely run BM3 stage 2 with only primary or secondary and not both?

[FloridaM5]

Originally Posted by iranjha

Also, does anyone have a simple answer to the pros and cons of primary and/or secondary catless downpipes? Trying to weigh whether I should do both or one and not the other.

I'm wondering in terms of smell and sound, in that order.

Ideally I want a setup that doesn't smell and sounds better than stock exhaust. Will I still be able to safely run BM3 stage 2 with only primary or secondary and not both?

Smell: if you get rid of primaries and secondaries, you will smell fuel. Whether or not that amount of smell bothers you is kinda personal….some are ok with it. I personally am not anymore.

For the goal you stated, get rid of the primaries and keep the secondaries. Get any stage 2 tune you want, and then go fast. You don't have to be fully catless to run strong stage 2 tunes.

With the primaries removed, yes, the car will be louder.

[FatRear08]

Stage 2 for a year now. Car runs fantastic. Not a single problem. I warm her up properly, don’t habitually beat the crap out of her, and drive moderately when I’m a short while away from parking(like a cool down lap).

[will0621]

Originally Posted by AngryInch

Ya, I agree, catless IMO would be better long term. The engine can breathe, the exhaust gas temp will likely be lower with the increased flow and lack of cats stuffed right behind the turbos.

The main thing is not too much timing for the boost and good quality high octane fuel. Also if you live in a hot climate, it wouldn’t be driving the hell out of the car…

I will also be running catless downpipes with a tune for the entire time I own this vehicle.

Are you going with DME or waiting for other flash tunes to be released for the LCI?

[AngryInch]

Originally Posted by FatRear08

Stage 2 for a year now. Car runs fantastic. Not a single problem. I warm her up properly, don’t habitually beat the crap out of her, and drive moderately when I’m a short while away from parking(like a cool down lap).

This is smart advice.

[AngryInch]

Originally Posted by will0621

Are you going with DME or waiting for other flash tunes to be released for the LCI?

I’m running JB4 right now waiting for tunes to become available. I don’t think dme is out yet to the public?

[iranjha]

Originally Posted by FloridaM5

Smell: if you get rid of primaries and secondaries, you will smell fuel. Whether or not that amount of smell bothers you is kinda personal….some are ok with it. I personally am not anymore.

For the goal you stated, get rid of the primaries and keep the secondaries. Get any stage 2 tune you want, and then go fast. You don't have to be fully catless to run strong stage 2 tunes.

With the primaries removed, yes, the car will be louder.

I was behind a catless 3 series just yesterday and could not stand it. It gave me a headache and my F90 is my daily, and I like to drive with the windows down. So it's safe to say I don't like it either.

Good to know about the tune. I'm learning so much.

So I won't smell fuel with secondaries intact, or is it just to a lesser more tolerable extent? Apologies for confirming but I've just seen so many mixed opinions on these forums about what to do for the smell. I very much appreciate your insight and everyone's collective help!

[FloridaM5]

Originally Posted by iranjha

I was behind a catless 3 series just yesterday and could not stand it. It gave me a headache and my F90 is my daily, and I like to drive with the windows down. So it's safe to say I don't like it either.

Good to know about the tune. I'm learning so much.

So I won't smell fuel with secondaries intact, or is it just to a lesser more tolerable extent? Apologies for confirming but I've just seen so many mixed opinions on these forums about what to do for the smell. I very much appreciate your insight and everyone's collective help!

Right on. Yeah, this can be a great place to learn for sure.

I had absolutely zero abnormal fuel smell running catless primaries, oem secondaries, and the Remus catback system. Smelled like stock. Sounded incredible, though.

[iranjha]

Originally Posted by FloridaM5

Right on. Yeah, this can be a great place to learn for sure.

I had absolutely zero abnormal fuel smell running catless primaries, oem secondaries, and the Remus catback system. Smelled like stock. Sounded incredible, though.

Awesome! Just when I was thinking I was going to return the downpipes I ordered. I'm running stock exhaust which I'm assuming is less "open" than your setup, so hopefully even better.

Not sure how things work in Florida, but I'm assuming even with secondaries, I'm still not passing emissions?

[FloridaM5]

Originally Posted by iranjha

Awesome! Just when I was thinking I was going to return the downpipes I ordered. I'm running stock exhaust which I'm assuming is less "open" than your setup, so hopefully even better.

Not sure how things work in Florida, but I'm assuming even with secondaries, I'm still not passing emissions?

Can't help you there. Florida is pretty lax on the emissions front.

[WOGBOY]

i had the catless downpipes installed with a custom tune, no smell at all however
it is very very loud at start up, i have asked my tuner if we can some how reduce the nose at start up., but it does sound good.

[AngryInch]

If you remove cold start from your tune that initial noise will be removed.