when u go for straight pipes you reduce the back pressure and lose alot of torque. think of it this way if you have a 2 straws, one bigger in diameter than the other and blow out of both with equal force towards your hand. which one will feel like there is more pressure against your hand? the big straw will just feel like a breeze. getting straight pipes does increase HP but decreases torque. your top speed probably went up tho(wouldn't recommend checking that out).