I would think that my Soul long tube race catless headers and a Milltec muffler is more like 15 HP. The Softronic flash, race 78 mm throttle body and Plenum certainly pulls it all together nicely. I would guesstimate is about 308HP @ 6700 rpm at the wheels. I did this to improve the flat spot in torque around 4500, which it certainly did. I have had no problems with this system in 4 years of use.The stock exhaust isn't that restrictive on these cars. Even going catless long tube headers and a better catback will get you less than 10HP to the wheels. Its not much of a difference.