Dolmar 7900 tuned Harper

[blt]

Hey , i am looking to the the Harper workshop  where i can tune a Dolmar 7900 to take part to the next World Logging Contest in Germany  web site www:wlc-germany-2008.com
I am representing Belgium and there is only 9 Dolmars in that contest at the 2006 Estonian edition.
Dolmar 7900 rs is not avaible no more .Appearance of the saw must be stock.
5 events are made with .325 21 bp x and 21 lp x Oregon
I am looking to incresase the size of the air filter .
On this forum there was a terrific  picture of a special exhaust ,was it from the RS

Cheers
ERIC