like mblgjr said look into getting something more along the lines of a dual action polish such as the PC or a g110.
Also what year, and color is your car. Reason I ask is because most of the s197 body styles have a very hard clear and correction can be very difficult. Menz polishes will work extremely well and finish well, however I think they are best suited to tackle harder clears. I believe that SIP and IP dont have the best finishing on a car with very soft clear. On the other hand if you have a soft clear then optimum would be the route to go. Optimum will not even make a dent into hard clear but will finish better than nearly anything on a soft paint.
I hope to update in a little with more info once I know year and color. This will help me deduce what kind of clear you might have. I can't make a complete deduction however because every car will be different and even models of the same year will have different variations of cc (clear coat), paint thickness and what not.
Hopefully this helps, btw I dont think a powerball is really worth the money, not once you get into the corrective side and what not.