Ed,
IIRC, that is the exhaust with a "step" design. (primary tubing starts at 1 1/2 inches, and steps up to 1 3/4 several inches away from the head). If so, I know that there was a lot of development and dyno time in the design of that header. I know the S&S header as well, but I think it will cost you power over the above mentioned design. If possible/practical, have a local fab shop replicate that header and tuck it up closer to the chassis. It will be more expensive than the S&S, but probably worthwhile.

I had more midrange power with the S&S set up (parallel merge collector--a short section of 2 inch and a smooth transition up to 2 1/2) than I did with the bigger headers and the 3 inch. It sacrificed some upper rpm strength though. (5500+)

If you still opt for the S&S for price or practicality, call and talk to Lauren. He has been building these things for a long time and is pretty helpful.

Joe H. probably still has more knowledge in his big toe than I do about these cars though.

Jim

p.s. pm or email me if you need more..