Don't worry...You'll love it
Well Turbodan...I've had my SMC kit for about 8 months now on my 87 GN. I'm able to run 20 psi of boost using 93 octane pump gas with zero knock retard showing on the Scanmaster. It will show a couple of degrees on the shifts when I'm really hammering it.
When I first put it on, I was going through a gallon of denatured alcohol in a week (Lot's of test-n-tune....yeah right...that's the ticket) I'm running straight denatured with a few squirts of grape flavored alcy top lube per tankful. The lube helps the pump out.
Now that the 'new' has worn off, I fill the 1/2 gallon tank about once every 2-3 weeks. I haven't been to the track yet, but I imagine a tankful would last 5-8 passes depending on how hard you were spraying it.
I'm not sure about warranty, but Steve C. at SMC is a straight-shooter and if you had any problems with the kit, he would make things right. The kit goes in quickly, looks good, works flawlessly, and is MAJOR fun. Once I got the feel of 20 psi of boost I was ADDICTED!!!!
It was the single best modification I have made to my car.
John