I've been running my MGT with the stock engine for over a gallon of fuel and for some reason it is make a very high pitch sound even at idle. I pretty sure that all fuel lines and exhaust manifolds are sealed. I also put in a new glow plug but still have no luck at solving this problem. The truck still runs ok but even with adjusting the settings, the sound pitch does not change. BTW I am running with an XTM pipe so I don't think its just the exhaust noise. Any suggestions?