[blue00gt]

I have BBK Longtubes on my '00 GT. It definitely was a pain - took me about 12 hours to do it myself. I only had to jack up the passenger side of the motor (about 3"). The rear header bolts on that side are extremely difficult to get to around the 4 tubes. If you do it yourself remember to tighten to make it easier. I definitely felt a good seat of the pants gain and the sound is great with the headers, short H-pipe and Magnaflows. Nobody believes me that I have cats on my car until they look underneath it.
The only other thing to watch for is ground clearance since they hang down quite a bit lower than shorties. My car is pretty low - lowered over 2" in the front. I ended up with a little under 3.5" of clearance underneath.
One other warning - my passenger side header sometimes taps the frame and makes an annoying noise at part throttle at certain rpms. I tried several times contacting BBK and never got a response from them, so I will not buy any more parts from them. I have had to adjust my driving to avoid the nosie. I've seen other longtubes for new cars made by Hooker, Hedman, MAC, and Sean Hyland.