Might be that rejetting would take care of the problem at speed.
If you do decide to get different baffles, it would be an interesting experiment to try them at different positions inside the pipe before bolting them down. Calculating the frequency of an exhaust system is really complicated but, if you can slide the baffles in and out to tune the pipes like a trombone, you just might hit the spot that will give you a big power boost just where you want it the most.
Just hope your luck is beter than mine. If I had an opportunity to try this, I would probably end up with a power gain too good to do without at a point that the pipes make a sissy 'weeble weeble' sound.
