Thread: N54 Backfiring?
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      07-11-2011, 02:21 PM   #5

Drives: 2008 Silver 135i
Join Date: Feb 2010
Location: Irvine, CA

iTrader: (5)

Originally Posted by evilstib View Post
Replaced stock midpipes with (previously owned) CP-e catless midpipes. The Downpipes & muffler are stock.

I love the tone, but I get a lot of backfiring now. I didn't think removing 2 of 4 cats and the resonator would cause this.

Anyone else see this before?
You are hearing some popping, which is totally normal. The same noises are present stock, just much harder to hear. When you remove two of the cats, the noise is amplified and you can actually hear it.

To get REAL backfire (flames out the exhaust tips), you'd need to be completely catless.
2008 135i MT - JB4 15ohm, Map 3

CM VC2 2.7gal Meth Kit | CP-e Downpipes | BMW Performance Exhaust | BMS DCI | Stett CP & Forge DV's | ETS FMIC | 3.46 Quaife LSD | KW V2 Coilovers | Breyton GTS-R's | Dunlop Z1 Starspecs | Complete BMW Performance Exterior & Interior