I thought meth kits were making a sizable difference? I'll see if I can find a basis for that information. On top of the cooling effect, meth is also a very high octane fuel, mixing it with pump gas, under specific criteria effectively allowing you to run a tune as tho you have a race gas. The down sides are (as I understand)
1) that meth is very corrosive and long term effects are as of yet, unknown. Current GT fuel system components are not suitable to carry the fuel. All parts need to be hard anodized.
2) this becomes another failure point that could lead to catastrophic engine failure with no early warning, should the pump go out or a jet become clogged. Or the more common, you run out of meth mid-pull. How much do you trust your $45k motor to the cheapest chinese supplier?
3) some people contend that if added before the intercooler, the weight of the methanol in the intake will be subject to more centrifugal force and roll the the outer most cylinders. Thereby causing hot spots in the motor. (a little far fetched but stranger things have been true before)
With that knowledge, I would say you can make an informed decision based on the information. I am interested, so let me know what you decide to do.