I was at Sand Mountain last weekend and tested out my 5 gallon drum of VP U4 for the first time. I paid nearly $50 for the drum (normally goes for something like $65) and seemed to have some very good results. Here are the current performance mods on my 440.

1) 440 bore with 13:1 Piston
2) Ported headwork
3) Web Shortened Valve Guides
4) Web 479 Grind Cam
5) Web Hardweld Rocker Arms
6) Web Performance Valve Springs
7) LTE Dual Exhaust with Airbox / K&N Filter
8) Edelbrock 38MM "Doug Eichner" Carburetor

Max Horsepower was 39.5 hp at 7250 RPM
MaX Torque was 32 ft-lbs at 7250 RPM

Altitude Tested at: About 5000 feet

I had to rejet the carb back 4 clicks leaner to get the best results. Unfortunatly, I dont have comparitive numbers against standard race gas - but it felt like about 2-4 hp more with the U4 fuel.

I did run the U4 out of the carb at the end of each day - I have had one friend that had problems keeping that fuel in his carb; it gummed things up after being left in the carb for several days.