i went to my local 99c store down the street they sell two 16oz bottles for 99c, you buy 8 bottles that puts you right at 1 gallon do the math 8 16oz bottles=1 gallon, heck for $4.00 i can dig that , just thought i share with you guys .
Iso can be used in the SMC kit just fine, but as Steve said there will be a slight perf dropoff, probably in the form of a little less boost/timing vs. denatured or methanol.
I would not put water in iso, as it usually has water in it already