i spent about 40 on drill flap wheels, and dremel parts, and 50 on regular sand paper. its a very hard DIY! well not hard, just takes a long time. you're going to start sanding away, and 3 hours later, you'll have about 2 or 3 square inches smooth (not even polished, 60 grit smooth). you'll have to go from 60 grit all the way to, i went too 800. i think. and then you can polish it.

 

alot of work, i would just buy it or work a trade for yours.

 

Not hard to do in terms of technical skill, just takes time.

 

I had mine chromed:

 

Nice

 

Wow!!! Good stuff

 

you do not want to polish the inside. as air flows with atomized fuel it needs to tumble. The rough cast surface is perfect for causing turbulance and allowing the air to mix further with the fuel. If you polish it then the fuel will not tumble and will actually condense on the polished surface causing inconsistent fuel mixture. I studied this greatly when working with the race bikes that i tune. We go for a smooth surface but you still want it to be turbulant, not polished. I port heads for race bikes all day long and test them on a flow bench. Polishing exhaust ports helps greatly on flow rate, but not intakes.

If you want to do anything with the inside then you can take out any casting flaws that cause an imperfection in the way the air flows into the intake.

 

u can polish anything thats aluminum