Some engines get the best gains from straight water, and some with straight methanol, and some with a water/methanol mix.  How much methanol, well that is up to what your engine prefers, and every engine is different.  We recommend to start with straight water, and then see the results.  Then, try a 10% meth/water mix, being sure to purge the straight water from the lines, and then see the results.  Do this for 20%, 30%, 40%, and 50%, etc....  If during this process, you notice your performance decrease, then don't try any higher of a mixture.  Revert back to the previous amounts and use what works best. 

There are many places to buy straight methanol, found here, but if you are going to use a water/methanol mixture, the easiest (and cheapest) is to buy the blue windshield washer fluid that is used during winter time to prevent the fluid from freezing.  It may sound cheap ($1.29-$1.99 per gallon), but it is just as good as any methanol/water mixture you would make otherwise.  The blue is just a dye, and an extremely insignificant amount (<1%).  Some of the washer fluids, such as RainX, contain cleaning additives, but this is easily determined by shaking the bottle and seeing of it suds up like soapy water.  If it does, don't buy it, but if it doesn't, then it is good to use.  There are many different brands out there, but they all have common amounts of methanol for their respective temperature rating, regardless of the brand.  We have many MSDS's (Material Safety Data Sheets) from different companies to support the following data, but only one per temperature rating is available for viewing, which is representative of all the brands (within a few percent) that produce that specific temperature rating.  To view the MSDS, simply click on the item.

+20 F Washer Fluid  -  Contains approximately 7% methanol.

0 F Washer Fluid  -  Contains approximately 23% methanol.

-10 F Washer Fluid  -  Contains approximately 28% methanol.

-20 F Washer Fluid  -  Contains approximately 35% methanol.

-25 F Washer Fluid  -  Contains approximately 38% methanol.

-50 F Washer Fluid  -  Contains approximately 62% methanol.