Sounds great for a stock car. A 5% pulley will net you a little more, but don't be fooled by more boost being better! A potato in each tailpipe should raise the boost over 15 lbs for a while, but is not a good idea!
If you are wanting to spend some $$$ and make mods, then start with opening up the exhaust. Then some intake goodies. You are really trying to get more air and fuel through the motor and not just raise boost pressure.