if you have the stock t-15 you do not need to worry about gear mesh as the engine has engine mounts built on and it just bolts straight on to the chassis. if you have a engine which takes separate engine mounts eg. lrp z18s pro then you will need to mesh the gears correctly otherwise you will strip your spur gear. there are two ways to mesh a gear and both work great. the way i do it is by getting a plastic baggie (like the ones you get from hpi spare parts). fold it over once and place it between the clutch bell and spur gear. apply a fair amount of pressure on the clutch bell and make sure the clutch bell is parallel to the spur gear and tighten up your engine mount screws. then roll your car foward to remove the plastic & see if it is meshed good. you will also be able to feel if it is a good mesh. it shouldnt be to tight, it should just roll along smoothly when pushed. 46u and others use paper and it works the same. i have used paper but it some times splits/tears. maybe its me and im using cheap paper.