It not a hard thing to do the rockers. It only take a few simple tools and about 3 hours (first time). I can change mine now in about an hour and a half. I did my port/polish and rockers at the same time, but I also had larger valves installed by a local shop. I changed out the rockers when I got the heads home. I have just installed a huge TB. I had to fabricate an adapter that probably takes away from the TB size a bit, but I didn't have money at the time for the sheet metal intake. The difference is amazing.
Simple fact... The better your car can breathe, the harder it can run!