I had the WR intake, Strup header, WR engine damper, and Strup exhaust installed. I did each separately so I can feel the difference. The intake was first, that made the car a bit louder but it pulls a little stronger than stock.. Id say maybe 1-2 hp increase at most. Then came the header, which didnt help much on the low end since its a 4 into 1 design, but mid to high end you can feel a little stronger on acceleration. Especially from say 60mph to about 80. The exhaust, since its a catback was a bit louder than stock, I would expect maybe another 2-3 hp increase there. I saw this huge submarine resonator in front of the exhaust, Im sure if I removed that I would see a huge increase in power but than it would be much louder as well. The engine damper vibrates a little but I did notice less hesitation between shifts on the auto trans, acceleration seems much smoother than stock.