I'm new to this group on the net but not new to auto performance. I will say I'm a big GM man, I have owned many different cars and trucks, from Trans Am's with 4.6's to my 97 Grand Prix. Out of everything you can do to an engine a great thing you can do is port and polish. For you how don't know what that is it boils down to making the air for the intake flow easily to the head and into the combustion camber. With most engines the areas around this flow is okay, but not perfect, you can buy kits that will fit a small drill and smooth the areas out, but not to smooth (I won't get into all the details.) To get to the point when I have done this to V8's or V6's I get about a 10 to 20 hp gain depending on the engine, Its just an idea for you all to try, and no I haven't gotten my engine apart....yet, so when I get it to that point I'll send an update.