You have to remember that if you have them tuned down, you will then have to have them tuned back up if you require higher power later on reducing port sizes, regulators, hammer springs etc is all hit and miss, you have to be prepared to get under the hood as well, mine was shooting well in to the 80's, and took a fair bit of work to bring it down to where it is now, with a good number of power shots, low noise and regulated power. this was not a bodge job, it was done for consitency as a hunting gun.

I am sure Jon will fill in any blanks in this region as he has a wealth of knowledge concerning these guns.