If you can find a carb restrictor anywhere, a 6mm would probably be just right for the buggy. I could only find a 7mm Orion restrictor, and that one helped only slightly over the 8mm that comes with the engine. The best pipe for this engine is the EFRA 2013. I've tried many different pipes, and this one brings the engine alive better than any others I tried. Run times are not very respectible though. You're probably looking at somewhere in the 8 minute range. The most I could ever get out of it was 8:15, and that was in practice.

http://www.amainhobbies.com/product_...ha-7mm-Venturi