What exactly was "bottoming out"? I'm a little confused as to what your original problem was.

I've installed a few exhaust systems including Pypes and haven't experienced anything bottoming out.
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1966 GTO
1969 Lemans Convertible- F.A.S.T. legal family cruiser. 12.59 on G70-14 Polyglas tires. 1.78 60'
1969 Bonneville Safari- cross country family cruiser. .
1979 Trans Am 400, 4-speed, 4 wheel disc.
View from the drivers seat racing down Atco Raceway-
http://www.youtube.com/watch?v=GhYDMdOEC7A
Ride along in the other lane-
http://www.youtube.com/watch?v=mIzgpLtF_uw