what advantages to changing headers on a stock d16z6 engine do? i presently have an sri and a freeflow muffler installed, and people are saying that the last bit in the equation should be new headers.

aside from the obvious improvement in engine response ( as i noticed with the sri), what other benefits to these have? any downsides to this setup? fuel consumption issues?

 

the only difference you will have is a louder engine. You"ll gain a couple horsepowers but noithing to be like "damnnn". and before people bash you, its header. there is only one.

 

Just wondering, is that muffler simply welded onto stock piping, or was the whole exhaust (after the cat.) replaced? If it was replaced, what's the size of the new piping?

What other benefits other than "bling" factor and a few (like 2-5) extra hp? Nothing that I can think of. No down sides except for the fact if you go turbo later on down the road, the header would be useless and would have to be pulled off. Your fuel consumption will not change with a intake/header/exhaust unless you start driving it differently.