2015 335 intake/exhaust question

[kitchener]

Replaced my old twin-turbo 09 335 a while back with a 15 335, and I've been missing that twin-turbo ever since. Fortunately, my amplifier died (user error) and the boss doesn't know it's covered under warranty -- I'm adding a Turner Stage 1 tune and colder plugs while it's in the shop (and a throttle booster -- had it on the 09 and liked it).

Probably a little later this month (to mask the outlay lol...), I'll add an intercooler. With that, I was going to add the M Performance Exhaust, but googling (and it's not exactly clear, hence the question), does a high-flow, catted downpipe offer more performance than the MPE, or are both more just noise oriented? I suggested to my shop the combination of the two, but he thinks combining them would be more noise than I'm looking for.

Assuming that's true, which would be more beneficial, performance-wise, a high-flow catted downpipe, or the M Performance exhaust?

[asrautox]

A highflow DP will provide better gains than a catback and the two together will likely not be any louder than just the CB. DP's don't really change the noise level unless you go catless. Also, IMO skip the Turner tune and go BM3 or MHD OTS map.. Those two are more supported on the platform and offer the ability to customize as you mod..

[kitchener]

Thanks -- with the Turner 90-day return, I'm going to do just that (it wasn't a happy marriage: CEL and stalls). I'm going to go FBO (IC+CP+cattedDP) and the MHD Stage 2+ tune -- hopefully it'll all go seamlessly.