VegasDelta, the TH300 was a two speed then..I didn't know that but it makes perfect sense with the 260 and you are right about the non-interchangeability (did I just type that?)
of B.O.P. parts to other GMs.
Mikkim, I think you would be happier with dual exhausts if only for the nicer exhaust note. All dual exhausts exited out the rear in one form or another. If you mean DIRECTLY out the back horizontally, on 442 models I think the bumper would have had half-moon cutouts for that or maybe even circle cutouts. You will have to check with some 442 guys on that one though. As for headers, many people make headers for the 455 engine, the question is will they fit your car, the f85 is pretty small and I am not sure but that you might have some fitment problems. Not to say it couldn't be done as I am sure it has been before. At any rate if you run duals, 2.5 inch pipes are a good size for the 455 all the way back and remember selection of mufflers makes a world of difference. There are lots of sound bites of peoples' exhuasts on the web, they like to share them with others after getting a new system installed so search around beforehand if you aren't sure what you would like. I don't think performance would be as paramount as sound and durability since you mentioned the car is for street not racing. Try a site called Realoldspower.com. You may find some sound bites there. Good luck and keep researching. BTW get the 455/th400 combo....
