If you are truly serious and committed about going fast then go here.

http://www.jettengineering.com

Purchase a BSE .40 engine, use an APC 8.5 x 7.5N prop. screw them on to the front of one those $80 Scatcats and go faster than anybody in your club has ever gone before.

The engine a little expensive? Yes but speed does cost money. If you are trying to go fast on a budget then you will remain down amongst the Duffers. That is the harsh reality.

Ed S