I have a 97 4x4 4.6 w/ 193k miles.
I was woundering if a set of headers would give much performance/mpg?
My basic questions are...
1.) How expensive would a set of headers be that gave me *noticeable* performance icnrease (Im not looking for 50 more hp... I am realistic, but I would want to be able to notice an increase in power and mpg.)
2.) How hard of a job is it to replace the stock exhaust manifold with a set of headers, is it near impossible to get the bolts out after all these miles? Does the gaskets come off easy? They connect my trucks H pipe&cats at a flange with bolts right no welding?
3.) Are there any 02 sensors or anything on the exhuast manifolds?
4.) I have flowmaster 40 series 1 in 2 out on my truck now, how would some headers affect the sound, I wouldn't mind it bein a tiny bit deeper.

Thanks ya'll.

 

the sound, not much.

The performance really depends on what the rest of the intake/exhaust is doing. All together, a free flowing intake and exhaust will give you upwards of 30 or so HP. Seems that the mufflers have been done, and with an H-pipe, and a set of high flow cats, you can expect somewhere on the order of 10-15hp total. Really the free flowing items work best when they are all in

There is an o2 sensor, so you will either have to find an set with a place for one, or weld one in yourself. Think that tig is the only way to get it to seal.

Headers being a pain in the butt is almost a proverb. You need a great penetratinglube, like PB Blaster, or Liquid wrench, and a lotta patience to get the old ones lose. To get the new ones on, you're gonna need a TON of patience. The thinner your sockets, the more likely you are to not have to use wrenches. The wrenches with the notch cut out of them to make a "ratcheting wrench" are a good thing to buy. other type of ratcheting wrench with the ratcheting box end won't even come close to fitting.

The gaskets aren't usually that bad. At least that's my experience. A good razor blade will help with this, as long as you're careful. A puddy knife is safer, but sometimes slower.

hope it helps.

 

I think this would probably be a bigger job than I would take on right now. Time is really tight right now but I am going to keep researching. The flowmaster is the only thing that I have done to the truck. Would a set of headers make the sound deeper, or just kinda open the sound up more, or just make it louder? Is the power gain in low end or high end?

 

high end power gain, the sound is kinda a crap shoot. The muffler makes the most difference here. I'd say it's gonna open it up a tiny bit, so maybe a bit brighter at the top end?

 

Headers will almost always make things louder. Being less restrictive, that means sound too. Want deeper? Bigger pipe will always help that.

Power gains can be high RPM, low RPM, or a little bit of everything, depends on the total design. Decide what you want before buying anything. Things like long tube headers will tend to boost low to mid range the most, but not take anything away from any part of the RPM range. Pipe size, and whether an H or Y pipe is installed (and where) will have an effect also. Shortie headers will generally give less gains, but not by much.

Any Header worth its $$ should have the hook-ups for your O2s, and fit right. R&R the headers is quite a job. Certainly not impossible though.

A good tune will make everything work together even better, but thats more $$.

 

A local performance shop, that I have known to be honest, a little pricy, but does good work told my dad several years ago when he was talkin to them about his 94 302, that a good set of hedders would most likely do more for power than a chip. Do ya'll think this is accurite? If I get hedders should I go ahead and have them cut out the 4 cats and install just one high flo cat or something? How restrictive are 4 cats with 193k miles on them?

 

I'd gues that they are clogging you up. The only thing that you ahve to worry about when you start going away from stock in the cats is that the o2 sensors have to read right. If they don't the engine will run rich, which means less power and more money, neither of which are a good thing.

 

You can get O2 simulators so your CEL wont be on. Besides, the second O2 sensor (the one behind the cat) has nothing to do with the air/fuel mixture. It's just there to make sure the cat is doing its job and not malfunctioning....