I got my 2009 Aprilia RS to 34.6 horses with a 154cc big bore kit, zeeltronic CDI, 34mm flatslide, pod filter, Jolly Moto Corsa pipe and corret jetting. I had it setup by the Aprilia race team in Dubai so I cheated a bit but it went like a rocket...I wish I never sold it as I spent a fortune on it...it also had brembo m/c. Marzocchi forks, Ohlins rear shock and many other bits.

Sounded lovely Here's a clip...

http://www.youtube.com/watch?v=GTNaNvU_8QY&feature=mfu_in_order&list=UL

EDIT - Wasn't 37hp, was 34.6
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1996 MC28SE (Honda Flash), 24,000KM - Drilled airbox, HARC Pro pipes, TYGA Hi-flo reeds, special manifolds, Ohlins rear shock & steering damper - SOLD

1993 MC21SP (Winner's One), 10,000KM - Drilled airbox, wire splice - STOLEN!!!

1990 MC21SP (Cabin), 20,000KM - NC30 forks, discs, calipers - EN ROUTE...