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Originally Posted by BlazerLT
Gah, more thread revivals from the DEAD!
DON'T DO THIS!
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Like he said...don't do this. Stick with a well-made cat back system like a Gibson or go cheapie at a local muffler shop: get your fav hi-flo muff and have the shop bend up some larger diameter pipe to replace the stock for more flow. Get a hi-flo cat if your want and quit while you're ahead. Wanna dual "look"; getta catback kit with dual rear outlets or have the muff shop do it. Put a true dual exhaust system on it and your gonna have to wire up a second O2 sensor with the second cat if you don't wanna send the ECM computer into wierdsville. To do it right, and ensure equal flow from both sides, you'd have to replace the existing cat with whatever you put on the new side. In the end, you can spend a boat loada moolah putting on a true dual exhaust and end up with a truck that runs like crap. Not to mention any emissions laws you might have to deal with.....
Want even better exhaust flow and an even tinner wallet?.....replace the cast iron "log headers" and slip on a set of JBA "shorty" headers.
You gotta computer controlled, fuel injected engine (throttle body?) and it is designed to operate most efficiently with a stock-like exhaust setup (single exhaust). With computer controlled fuel injection it's easy to make improvements to intake and exhaust flow and have the computer make the needed fuel mixture changes. Back in the carb days, any improvement in overall air flow through the engine meant time spent tweaking the jetting of the carb to adjust for, and take advantage of, the increased airflow. Today the computer does it..... well, up to a point. You can actually improve the flow (intake and exhaust) such that it will exceed the computers ability to make the required fuel mixture enrichment..... then you run lean, don't make all the power you shelled out the big bucks for and the engine runs hot.....
Got a TBI? Check out Turbo City (
www.turbocity.com): they are the GM TBI gurus. They have stuff so you can get the stock TBI to really perform.
"Performance" chip? Bag it...they only work at wide open throttle settings where the Feds let emissions requirements slip a bit. Under normal driving they have to meet the same EPA emissions requirements as the stock chip. Buy a 160 deg thermostat and enjoy most of the effects for a whole lot cheaper.
Clean up the intake track: these trucks have a variety of intake "mufflers" all designed to reduce intake roar....the effect on your motor is like trying to breath potato stuffed up your nose. Look yours over and see what is making it harder for the engine to breath...simply remove it. Best of all...it's FREE! From the "oldies but goodies": look at your air cleaner you may be able to flip it (unscrew the whing nut, remove air cleaner cover and flip it upsidedown... reinstall). This will create a poor mans 360 deg intake but.... you'll be sucking in all that hot underhood air, but.... it does sound cool.
Oh yeah.... try doing a good old fashioned tune up.... plugs, wires, cap rotor.... check the timing, set it to factory specs and don't screw with it; the computer controls it but it *must* have a solid basic setting to work from; in computer lingo "garbage in. garbage out".
Bottom line, it'll take *a lot* of money to turn this taxi-cab motor into a screamer.... Heck, you could probably swap a late model 4.3 out of a hi-zoot "Cyclone" optioned truck (or whatever it was called with the HiPo 4.3L) and be money ahead bsed on what your talking about doing here.
mike