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Dual exhaust blues

I have an'01 Z71 w/ the 5.3. I have added a high flow air filter & throttle body spacer. That gained me noticeable horsepower and about 3.5 mpg. Recently I purchased a cat back (these trucks have two converters) dual exhaust (2.5") & two 40 series flowmasters. I cut my "Y" pipe just before it turned into one one pipe, welded both flowmasters to the pipes, then ran full duals out the back. My problem is, since I've done this, the performance has stayed the same at best and my mpg has dropped at least 2 mpg. To all you mechanics out there, what the hell is the problem and how do I fix it? The only thing I can think of is possibly a back pressure problem. Any help would be appreciated. Thanks in advance. Brian

Reply to
Brian
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Mebbe your truck has the dreaded but common "heavy right foot" syndrome... Sounds so good ya hate ta stop... Tim sends

Reply to
Tim

I looked into doing this a few years ago and what Flowmaster told me was that you really should go from both cats into ONE flowmaster exhaust, then duals out for the pipes. He said you actually gain more power this way than "true duals". Call flowmaster (their # is on their website). They're really helpful and can tell you what's good and what's not for your particular vehicle.

Reply to
Tiger

I really have no idea, but would having a crossover pipe cut in befor the mufflers help to elqulize pressure and maybe help. Having one muffler on there befor was doing the same thing kinda.. anyway. just curious, how do you like the sound of the 40 series? thats what I want to put on my truck, also what throttle body spacer do u have?

Adair

Reply to
Adair Winter

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