What would be more practical to install first due to limited budget, a set of good headers or cat-back system or muffler only? how much more power would each give? This for an ES model.

 

HEH first off welcome to the forums, your probably gonna get a lot of negetive replies (i hope not) to this question.

But most likely you will be more satisified wit hgetting catback exhaust, since only a muffler and stock piping wont do hardly anything. you can get this done at a shop for pretty cheap :P
headers wont help much w/o the other piping too so work your way up ^_^
maybe get a pulley first if you havent already

 

what exactly does the pulley do? price? what type of gains/loss does it give?

 

well i'm planning on getting mine from a2 designs because it comes with belts, its about 90 bucks i think and it weighs like 1lb
i hear it gives nice gains and u can feel the power ^_^
+its like 20 min to install

rrm carries one too and you can use stock belts, they're having a xmas special till jan. for 80$
http://www.roadracemotorsports.com/
a2 designs

 

I don't think there is a "practical" 1st mod. I've seen a lot of people start with rim/tires, headers, body kit, intake, coils, , piggyback, etc.; it's all up to you.
On your limited budget, all those mods wont yield more than 4hp/trq at the wheels.I don't think you would get anything out of a muffler only. Just get a whole cat-back.

-Grey_Fox

 

Exhaust mods yield very little gains on a stock engine and in many cases can actually reduce overall performance. In my opinion it's best to get the intake side of things done first before you go opening up the exhaust. This means intake, throttle body and intake manifold. If you do those first you should get some decent gains when you install a header and an exhaust system without losing low end power.