Thank you for your advice. I will try the buffing first and see if I like the results.

Maybe clearcoat them afterwards?

how long does it take them to get stained from the exhaust ususally?

Mine still look new but then I don't drive it in the salt and wet.
Since I removed the Cat, they get black a lot quicker and I have to rub them down with solvent frequently.
One year I did drive in the winter salt, I had to buff them up after a light bit of fine sanding and that brought them back to new again.
Don't really have to clear coat them but periodic cleaning with a good solvent paste cleaner is recommended.
The aluminum is good and thick and as long as you don't let it progress to large pits, they can be cleaned up very well.
Not something you can do with chrome.
Stainless steel is good but harder to refinish when the luster is gone...but possible.

Another cheap way to pick up some power is to port the stock Series II manifolds. Well only the front one, the rear tubular cant be improved because of the way it'* designed. But the front one that is cast can be ported out (to port the floor you have to add filler material, ie welding on the outside on the bottom of the port so as to not go through, its very thing.) Also open up the roof (where most of the exhaust gas is and work it about 1-1.5 inches in and should be good. Also clean up the end that connects to the crossover, helps the transition as well (clean up the casting flash, etc). If you do this, the front manifold outflows the rear tubular by about 10-15% when we tested it on our flowbench. Hope that helps.

I've read that when porting, make the exhaust manifold holes bigger then the head exhaust holes, this is to create almost a vacuum effect. Leaving the lip in there like that.

Yup. Stay away from chrome tips. I made the mistake and fell for the tips Alex Exhaust had left over from their bulk order for the MNCGP mod day. Gave em $96 for both and less than two months later they are rusting around the outlets and looks as though one has chrome bubbling. I plan on swinging back in at Alex Exhaust tomorrow as I debated with him on this issue when he was trying to sell them to me over the SS'* that I wanted and finally I agreed to buy the chromies when he said he'd gauruntee them for 1 yr.

Now if I can get the GMPP tips from a GMPP exhaust for GP'* I'd be happy.

Stainless steel based tips are the best. Keeping them clean and coated well is also a huge advantage.

i just got a magnaflow 3.5 inlet dual 3.5 outlet. they used the stock pipes coming out of the muffler and made an adapter to go from the 2.5 to 3.5 muffler. then they cut off the stiock tips and put some magnaflow tips on as well. i love the sound comin out of it, drove around the high school soccer and softball games and got the typical "Is that a bonneville?" as they heard it and saw the ram air hood scoops. hehehehe

sounds cool, got any pics of your ride?