Not trying to brag but just wanted to share info with everyone.
I just had a 3 Inch Downpipe and High-Flow Cat Assembly installed that I purchased from Hoganperformance.com. I'm sure it increased my HP by 11 HP. It is great sounding with my dual Dynomax Super Turbo Mufflers. Not raspy sounding. Not too loud either. It has a low mellow sound. Curt Hogan was very helpful when I had alot of questions that I needed to have answered.
NOTE: This is for the 97-03 Bonneville with a 3.8 *.C. or 3.8 N.A. engine.
Dave SSEi, 2001 (black).

11hp? where did you get that number?

their webpage:

http://hoganperformance.com/DP8S.htm

:? must have been the super secret verision

and they did 2 dyno pulls for each, and we all know that dyno pulls can vary from pull to pull...11hp...if your not decently modded you prolly lost lowend

With the rest of the exhaust being 2.5 (assumption) his backpressure should still be there, however the initial pull would be stronger because of having a place to stack the exhaust.

Stack the exhuast? WTF are you talking about. How long do you actually think it takes to fill that space with a volume of exhaust gas? Anyway, it makes more sense to have a smaller dp and a larger diameter exhaust tubing after the downpipe. The reasoning behind this is that the exhaust gas has the highest velocity exiting the ports and it'* fully expanded (heat). As it cools going the exhaust the gas slows but takes up less space. By going from 2.5" to 3" after the downpipe you are creating "backpressure" (which is one of the biggest myths in the automotive world ever).

CW...this is not the place for your debate. Back on topic please.

FWIW - I was the one that provided the dyno sheets to Curt. It was my car and my experiment. You can see the results here:

http://www.bonnevilleclub.com/forum/...=583005#583005

My mod list is in my sig. These results were with the stock cat and exhaust.

Congrats Dave...glad you're happy with the results.

Tommy... great info and thank you for being one of the first, if not the first to give it a try.

That was on topic. It'* just that you said something with no reasoning behind it. I was more on-topic than you were.

You should have posted that as your original reply "this is off topic." This whole thread is about a guy who is bragging about his new downpipe.