The list bloodSHed gave, with the addition of a 3" x 8" flex pipe, is what would give you the highest whp gains for an exhaust setup. It will be louder than the Mugen twin loop. I personally went with Kteller's 2.5" piping in stainless steel.
3" Kteller Exhaust Piping Kit - $238.50 + shipping
3" x 18" Vibrant Resonator - $103.33 (free shipping)
3" x 8" Universal Flex Pipe - $19.49 (free shipping)
3" Vibrant Muffler - $134.50 (free shipping)
3" Magnaflow High Flow Cat - $75.74 (free shipping)
Those are prices I found on Kteller.com and eBay. Total is $571.56 for that list, plus shipping for the Kteller kit. I would put you at $600, for an exhaust that would crap on a brand name $700-1000 exhaust.
As far as the header situation goes, the Hytech replica is the header of choice for a lot of prelude owners. It is much cheaper once again than brand name headers out there like the $500 DC sports and Greddy choices. You would be looking at around $250 for the Hytech replica. 11whp dyno proven on a stock prelude.
Basically you get a sweet header and exhaust for less than a Mugen twin loop.
Last edited by That 01 BB6; 01-08-2013 at 11:06 PM.