True, and yet this topic has probably been discussed more than anything else around here. Lets face it, with any N/A car any style intake and any style exhaust is NOT going to yield any more than 10-12hp on average. Its just not within the realm of possibility. SO for those ebay adds that boast "air intake scion tC gain 15-20HP" you gotta just laugh. The TRD exhaust is purely a "sound" mod. It does nothing for horse power. But then again, i'm not sure that any of the axle back systems do. If you want to boost your power a bit... well enough to feel... get an intake.