Ok so I got a cracked exhaust manifold on my 4th gen ex and I was thinking of just putting a header in. I have a few questions though. How much more heat will the header add to the bay? Would it affect a cold air intake? Would my exhaust be much louder if I kept the stock piping and muffler? I need the cheapest possible, does it matter what brand or anything? Should I get a high flow cat and keep the stock muffler?

I am trying to gain hp, but not really have a loud *** exhaust!

 

if you get an aftermarket header and still run the stock cat-back it wont be loud at all.

 

it should sound pretty quiet...you might have a slightly deeper tone, but other than that it shouldn't be very noticeable from outside the car...don't invest in a "high-flow" cat...a cat is a cat, and they are all plugged with restrictive ****...if you don't live in an emmissions checking state, go ahead and chop that bad boy off...it should yield the most gain along with a full exhaust...but don't expect any kind of quiet exhaust note...sorry to go off on my own little deal, but to answer your question, an aftermarket header will add heat to your engine bay since there isn't a shield and the unit isn't made of the dense materials that the stock unit is...but by all means, do not get a DC header...

 

for cheap replacement just goto junkyard/ebay, and it wont affect the temps cuz CAI is outside of the engine bay so the heat would have no influence outside of the bay...