Gumby

How does back pressure work?
Why do you lose bottom end torque if you reduce back pressure?
I've always wondered about this, but could never figure it out.

cliffyk

It doesn't back-pressure is bad, however reverse flowing pulses from a tuned system are good--read more here...

Gumby

Thanks for the info...this helped clear things up.
What puzzles me though, is a buddy of mine installed LT's on his 99GT and he said there was a small drop in bottom end torque. Maybe he's full of crap, I should tell him to put it on the dyno.

I clicked on the Miata link in your sig. Sorry about your step daughter, she looked like a real nice girl.
Images and stories like that really make me glad I don't drink and drive.

cliffyk

As stated in the S&S"101" document headers can be tuned to do a bunch of things, just not all at the same time--the designers often sacrifice low-end torque for high-end and vice-versa. The system you're replacing woould have to be very bad to see gains all across the band...