Headers & powerband...

[Weirdo_Joe]

Alright, with my current setup: a 3" Chrome Intakes CAI, a 2 1/2 in Magnaflow muffler, underdrive pulley... my fastest acceleration is in the 4k - 5 1/2k RPMS (powerband, right?) I am planning to get headers from xiaogary, and then do a "cat-back" exhaust sytem... my question is: will the headers move the powerband? And with the current setup, (+headers) what size exhaust from catalytic converter to muffler would ya'll recommend? I'd like to advance the powerband to lower rpms doing the exhaust, if possible! I've read the exhaust/intake has a huge effect on this...

[petrified.rabbit]

the more flow you add the longer the car can pull without starving for air..

then eventually fueling cant keep up (wont likely happen in bolt ons).

[Weirdo_Joe]

Ok, so soes that mean the more flow you have, the higher your powerband will be? Is it when it is "starving for air" that the powerband kicks in? If so, should I consider maybe... only 2" exhaust, as opposed to 2 1/2" or 3" if I want to have more power at lower rpms? Thanks rabbit... I always appreciate your knowledge!

[thehunterooo]

should increase from 4500 and up or so, if you dyno'ed the hp line would shift upwards towards the higher rpm's more than it would in the lower rpm (or even decrease in some cases), 2" exhaust should be all you need.

[Weirdo_Joe]

Thanks Hunter! I just wanna make sure that these modifications will not "push the powerband too high" as I read somewhere, that doing an exhaust that didn't match your intake could do... thanks again, everyone! Car mods are lots of fun!

[petrified.rabbit]

depending on the type of bend the muffler shop does, and how many piece of equipment (muffler, resonators etc) you put in, you will only need 2 - 2 1/4" exhaust. the more "free flowing" the set up, then step down to 2". The only way you would possible need more than 2 1/4" is if you have turbo..

this will give you the most lower rpm and be more than enough for the top end flow. Even the stock exhaust mid section is acceptable with a good muffler.

the "powerband" question simplified, "ideally" you want to allow the cams to be the only thing that restricts air flow. so opening up the restrictions elsewhere in the system (intake and exhaust) eliminates premature starvation outside the engine block. thats really simplified.. to almost sound wrong.

[Weirdo_Joe]

I appreciate the simplified explanation... I am still a beginner, as you know. (I read the stuff about the intakes compared to a straw/spitwad... seems a smaller diameter intake leads to more power in lower rpm range? Less power later, right?). But I'm REALLY glad you brought up the turbo, as I meant to mention a note about that; maybe not NEXT summer, but the following summer... 2 years down the line, I anticipate... I DO plan to add a turbo system, and want to make any modifications leading up to that that would be preparatory... with that in mind... should I maybe go with 2 1/2 (or more?) all the way? I'd like to find a good balance of what I WILL need later, and something that'll add power, now. I know this topic has shifted somewhat, but it's all stuff I want to find out before I do any exhaust work (beyond the muffler I have) Thanks again, guys! Hope everyone had a great weekend!

[petrified.rabbit]

your car will suffer more having to big of an exhaust for a naturally aspirated engine, than too small of an exhaust for a turbo..

if you are planning to turbo, set the money aside and add it to the turbo build, along with the header money (header needs taken off for a turbo manifold)... and start planning your turbo build.

[Daox]

I completely agree with Rabbit. If you're planning on going turbo don't bother with the exhaust/header now. Put that money (which is a decent chunk) away and use it toward the turbo stuff. Tuning the car for natural aspiration is quite a bit different than turbocharging so you end up redoing a lot of stuff if you go one way and then choose the other.

[Weirdo_Joe]

WoW. Daox, rabbit, many thanks! I felt kinda silly after my last post; mainly 'cos I'm planning for something SO far ahead, but dang! I'm glad I brought it up. I was gonna buy headers this x-mas... I am already stashing away a lil' cash here and there, saving up for a turbo setup ( I am guessing around 3 grand? How close is that? : ) This helps me focus on gearing up for turbo... I will start a new thread for "pre-turbo modifications" so it's more relevant... I appreciate these very informative comments, and would also appreciate any other advice leading up to turbo; like what CAN I do? But that's a whole 'nother thread...