Quote:
Originally Posted by JasW
Well, the Cobb catted are in, but the rasp isn't totally gone. It's not always present at the 4500-5500 RPM range, and when it is, it has less of metallic edge; but it's far from sounding like I've gone and put the stock DPs back in. Not sure if the difference is enough to have warranted bailing on the AR catless (which I will put up for sale shortly).
I'm wondering if I should put the secondary cats back in and lose the Vibrant resonators. For all I know, the secondary cats combined with the primary cats might make a difference.
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Hi JasW, did you ever figure out what worked best?
I'm trying to learn from your experience and do the same for my 335is.
My idea right now is absolutely no rasp/smoke while adding more flow/performance so I can go Stage 2+.
I will keep stock downpipes with HIGH FLOW RACE CATS replacing the stock cats, I assume this will help the rasp, as you explained the catted high-flow DPs helped your situation.
Will add 2.5" x-pipe and keep stock 335is muffler without any mods to it.
Did you try to figure out if secondary cats work better than 1792 resonators to cure rasp and dampen noise?