Was the head leaking before you took it off? You should have at least one metal shim they call it which acts as a gasket to seal it. All so when tightening the head bolts you should do it evenly.

In the manual there should be the factory settings. If you do not have the manual you should be able to down load it off the HPI web site.

See if this help you to tune, as tuning can be a pain stacking learning experience!
http://www.*********.org/cars_eng-tuning.htm

Number one rule about this hobby learn to do all your own work!

Good Luck and have fun.