What can ya do?
Razor,
Yes, I'll do it. It takes less than an hour counting the time it takes to put it on the test stand and check it out.
The actual procedure involves removing a slight amount of metal from the upper edge of the exhaust port in the sleeve. If you look in the exhaust port, you'll see about an 1/8" of brass hanging down into the exhaust area of the case.. If you remove some of that, then it allows the pressure wave the pipe creates to ram a little bit more of the un-burnt fuel-air mixture back into the cylinder before the piston closes the port. That's what a pipe does anyway, but by increasing the duration, you allow it to do it's job a little better. Only drawback...you now have to run a pipe, always. If you put a muffler on the engine after the mod, all it will do is allow that much more un-burnt air-fuel mixture to shoot out the exhaust and performance will suffer.
Judging by just looking at your header/pipe set-up, I don't think you are fully tuned. Ought to get a lot more than 13K on an 11X7, too. When the pipe is set, it should sound rich and blubbery, then really leap up in RPM when it comes on. You'll know it.
If you would rather, I can send you a modified and fully broken in Rossi 60, you can swap engines, decide if you like the modded one better or not, and then decide if you want to mod yours. That way you can "try before you cut" and see if this will be enough of a performance increse to warrant carving on your engine.
Rudeboy,
Actually, the chrome in the top of the port is the hardest thing to cut. A tungsten carbide spiral cutter won't touch it, but will cut away the steel of a crank, no sweat. The only thing I have ever done on a crank is increase the closing duration 5 degrees or so.
IMHO 170 degrees is too much on an engine turning less than 19K or so.