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NEUMANNZZ · 10-29-2008, 01:08 PM

If the cat is plugged up(excessive backpressure) yes you can have problems, but usually not at idle, usually under load. a 2 inch in/out muffler shouldnt cause an issue unless its plugged up too.

10-29-2008, 01:08 PM	#94
NEUMANNZZ GMC RULZZ Join Date: Mar 2005 Location: San Diego Age: 43 Posts: 9,780	Re: 1991 chevy 1500 5.7 tbi erratic idle If the cat is plugged up(excessive backpressure) yes you can have problems, but usually not at idle, usually under load. a 2 inch in/out muffler shouldnt cause an issue unless its plugged up too. __________________ O2 GMC RCSB 4.8L V8 AUTO 3.73's rebuilt/beefed up 4L60E(at 43,000miles) Matching Ninja 500r