QUOTE(no0b123 @ Sep 17 2007, 07:45 PM)
For the exhaust, would you recommend the whole kit to be done (pipes and everything) or a new muffler, and good tips welded on?
And also, I have a new K&N filter installed which made a HUGE improvement for my truck in throttle response, would you still recommend I spend more and upgrade to a cold air intake, or stick with the air box and the K&N filter?
I was considering modifying the air box, and adding a throttle body spacer too. Would these benefit me at all?
Every car is different and every car responds differently to different mods.
The absolute best thing to do is hit up a Chevy truck forum and find out what other people have done to trucks just like yours and which modifications they had good success with and which modifications they had poor success with.
The reason being that These days a lot of manufacturers actually use really good equipment in terms of things like intake and exhaust. If they designed their intake well... then replacing it probably wont do you much good, but if they designed their exhaust poorly (or rather "cheaply") then it would be more beneficial to replace that.
Either way improving your vehicles ability to breath through spacers, intakes, and exhaust is a good place to start with power-adders.
Intakes are usually hit or miss. I know on my Subaru results were pathetic with after market intakes making almost no difference at all and in some cases actually being worse than the original factory intake
The exhaust on the other hand made enormous differences. Similarly spacers will work well to improve performance on some engines, while actually reducing performance on other engines... There is rule that works for all cars, every car is different and responds differently.
Some general tips
For an Intake
-The colder the air the more dense the air is, and the more air it can fit in the cylinders which = more power
-Shorter/smoother/larger diameter pipes = easier breathing and more air etc...
For an Exhaust
-Shorter/Smoother pipes = easier breathing allowing the exhaust to escape faster. This means pipes with less bends, and less extreme bends, and pipes with smooth internal surfaces "mandrel bent" is an important term as it means that the bends were made with a mandrel (a piece inserted into the pipe while bending) sot that the bends make a smooth curve as opposed to a curve with the metal on the inside edge getting all crimped and wavy.
-The more you replace the more you'll gain... Out of the engine the exhaust fumes go into headders which collects from the individual cylinders and flows down into a single pipe. From there it goes into a catalytic converter for emissions, and then into a straight pipe and finally into a muffler before exiting. Sometimes there will be a resonator on the middle pipe or a second muffler or a second catalytic converter... all are used to reduce noise and harmful gases.
The fewer things you have on your exhaust the better your performance will be... For instance if you removed your exhaust completely you'd probably have the best performance possible but you'd also have an unbearably loud vehicle spewing nasty smoke out of the engine bay
So what you're trying to do is make the exhaust as non-existent as possible
Replacing the muffler will help a little bit, replacing everything from the catalytic converter and back (called a cat-back exhaust) will help a whole lot more... replacing the entire exhaust including headers and the catalytic converter could make a world of difference. Of course it's expensive too.
Personally I would say don't even bother unless you can afford to do the cat-back, a decent cat-back runs about $500, you can get a hi-flow cat for about $100-$200 if you decide to do that too... (or if you hate the environment you can get a "test pipe" to replace the cat with just plain pipe for about $50... but you'll likely not pass your next emissions test). Headders can run from $500-$1000 and in general don't need to be replaced unless you're hard core serious about your performance.
Bigger diameter is not always better on the exhaust of a non-turbo vehicle. depending on the header design there is an optimal diameter that will actually cause momentum in the exhaust flow. Basically it need to be small enough to restrict the flow just enough so that the individual exhaust pulses compress into a single smooth flow, but not so much so that it actually blocks the flow.
Again start looking around and seeing what people recommend. Pickup a few magazines and look for exhaust or intake "shootouts" where they test a whole slew of systems and give you price and horsepower numbers.
90% of building up your car is research...
once you've got the intake and cat-back settled how you like it then you can start looking at computer stuff.This post has been edited by twistedsymphony: Sep 18 2007, 03:01 PM