Catless Downpipes Stink?

[Drive4Fun]

I had catless dp's on my 335 and they would choke me up a little if i let my car idle while i was around it. Outside or in the garage with the door open. Should i expect the same with the M4? I wanted dp's with flex joints but the only catted ones i have seen,AFE, dont have them. I try to be considerate and leave my garage door down on cold starts, not really sure if it helps a lot, but didnt want to pass out from the fumes.

[VCP]

I have Zima Ceramic DP's and it does not stink. The secondary cats do a very good job

Originally Posted by Drive4Fun

I had catless dp's on my 335 and they would choke me up a little if i let my car idle while i was around it. Outside or in the garage with the door open. Should i expect the same with the M4? I wanted dp's with flex joints but the only catted ones i have seen,AFE, dont have them. I try to be considerate and leave my garage door down on cold starts, not really sure if it helps a lot, but didnt want to pass out from the fumes.

[TRKY]

Originally Posted by VCP

I have Zima Ceramic DP's and it does not stink. The secondary cats do a very good job

Is there any noticeable smell when idle? Also is the sound similar to stock when the valves are closed in the exhaust?

[Ranoz]

Originally Posted by Drive4Fun

I had catless dp's on my 335 and they would choke me up a little if i let my car idle while i was around it. Outside or in the garage with the door open. Should i expect the same with the M4? I wanted dp's with flex joints but the only catted ones i have seen,AFE, dont have them. I try to be considerate and leave my garage door down on cold starts, not really sure if it helps a lot, but didnt want to pass out from the fumes.

you must have N55 335 which does not have two small cats not like N54 335 or the new M3/4. I used have the same stink smell on my 335, but not with my new M4.

[YMB_F80]

Originally Posted by Drive4Fun

I had catless dp's on my 335 and they would choke me up a little if i let my car idle while i was around it. Outside or in the garage with the door open. Should i expect the same with the M4? I wanted dp's with flex joints but the only catted ones i have seen,AFE, dont have them. I try to be considerate and leave my garage door down on cold starts, not really sure if it helps a lot, but didnt want to pass out from the fumes.

Mine is fine with the stock exhaust setup, during cold start if you just let it sit, it will smell a little but nothing crazy.

[NorCal f80]

I'm more worried about soot on the rear bumper with catless DPs and secondary cat removal.

[Mike@N54Tuning.com]

Catless downpipes with stock exhaust is a great combination for many reasons including the smell factor

As mentioned above the N55 e-series do not have secondary cats like the N54 e-series.

Mike

[VCP]

I would say no noticeable smell at idle, unless you are locked in a garage, lol. Yes, with valves closed it is not much louder than with stock DP's.

Originally Posted by TRKY

Is there any noticeable smell when idle? Also is the sound similar to stock when the valves are closed in the exhaust?