It should be 2 in
The stock exhaust diameter is 2 inches
I believe on the grand prix's form 97-03 it's 2.5" I own an 02 gtp.
2" diameter piping
One place to get parts for a 1970 Pontiac Grand Prix is at the website Stock Interiors.
2.25
6-8
3.8
Yes
260 hp and 280 tq.
3.8" inches
6-8 on stock 3.8 pulley. max is about 15-17.
my Magellan maestro showed 142 mph in a stock 2007 grand prix.