I can't speak to widening the exhaust ports.

But, yes, porting and polishing is worth it. Done right, you will see an appreciable difference in output. (Your results will vary.)

Inside is a rough, unfinished metal surface. When you have it polished, they mechanically push through this gritty, concrete like substance to smooth out the finish. When the job is done, the inside will have a near glass finish to it. This is what enables the air flow to increase.