I've been looking, and I think the HKS hi-power unit has a superior flow design. As well as the best price at about $580.00 at AMZ performance.

What do you guys/gals think?

P.S: my exhaust(stock) is kinda back-firing when rev'd around 3k and 5k when I let off the throttle. Normal? or something else...I checked the ecu and it flashed a normal condition with the LEDs.

HKS supposedly dyno's the most HP gains.

least amount of bends.... i like the HKS but lots of people ... well some... will say its ricey or some crap. sounds nice and very affordable i say do it. but best exhaust... really no such thing... peoples tastes differ and junk. and all cars back fire but usually like on occasion. and usually only noticable with a louder exhaust. mine did it a few times when shifting gears. but not just on a rev.