Years ago I dynode my stock 98 srx with a land and sea dyno and got 133hp at 8350....then did the cylinder lift and got 138hp...same rpm. Lastly got some ported cylinders done by Darcy Rosentretter and made 145hp at the same rpm. These are corrected hp. Grass Dragged this sled and with a Bender can was one sled length quicker. Ran against the same sleds with and without the bender can and was quicker with the can on. Did the can lose hp, don't know, was I quicker with the Bender can, yes by one sled length. Never had the can when I had the dyno or would have tried it. Pipes are like camshafts on cars, they determine the rpm that the engine likes to run at, unless you start to play with timing. Dynoed my 800 vmax and tried a 3 degree key, never changed the hp just moved it up or down 150rpm. Ended up with it making 159hp, and still passing tech! Was it quicker than my srx, you bet. Don't give up on your dyno, as you use it you will know when you made a good pull and when you didn't. Also srx tach was bang on. Had the optional pickup that was on the dyno, not hooked up to the sleds wiring.