[buddyboy]

Originally Posted by bigdonnyd40

I recently installed the CG DS-1 High Flow Catted Downpipe on my 540i. The performance results were positive; slightly increased volume, slight burbles on off throttle, and possibly a placebo effect of the throttle being more responsive, but it's there. I'm currently running BM3 Stage 2 as I'm waiting for the TU fuel pump that I ordered to arrive (when it does I plan to go Stage 2+), but I must say.... this thing smells awful.

I was really hoping that it would smell similar to stock but it truly smells like I'm not using a catalytic converter. I was enjoying a spirited driving around town last night and I was getting nauseas in the car due to the exhaust smell.

Unfortunately, I didn't realize that a new downpipe gasket didn't come with the kit until my old downpipe was off the car so I had to reuse the old gasket, but my car is fairly low miles, so I doubt that is the issue as there is no audible exhaust leak.

Has anyone else deal with this issue? Does it get better as the car "breaks in" the new cat (doubtful but hopeful). I'm a little upset with the outcome here and I'm thinking about returning the TU pump, putting the old cat back on and just keeping it stage 1 (which sucks as I came from a twin turbo V8 and was hoping to get the legendary bolt on power from the B58).

Thanks.

Those downpipe gaskets are single use, so thats most likely your culprit, you probably have an exhaust leak at that join and its getting sucked in through the aircon, also check the clamp on the bottom of the downpipe and both sensors are snug.

I've no issues with smell into the cabin with my old VRSF sports cat , so you should rule out a leak first