Hey Don hows things mate polishing and porting throttle bodies will prob see you enough bhp to count on your left hand. Best place to start on a budget is a good service. Also something over looked by a lot of people which I have always found good improvements with is the cleaning of your cam sensor. This is a nice easy weekend job. This will help claw back some of the stock BHP you may have lost over the years. Then again move with your air filter and exhaust but as said you may get 10bhp for a lot of cash spent. If you can go for a BMC CDA it will prob be better. Good luck and let us kn