Well, in a short answer, yes & no!!!!! Some go with the school of thought that up will improve the ride and handling.... I'm a Hot Rodder and a racer. I like to have the pinion angle down 3 degrees at "launch" height, or normal ride height. As the car launches the pinion has a tendency to climb up the ring gear, and move towards zero...actually, under acceleration I would choose to have it at 1 degree down. Under normal setup conditions with the carb mounting flange level at 0 degrees the transmission will be slightly down or level.... Now, others say that the sum of the transmission tailshaft angle and pinion angle when added together should come out to zero. Along with this most prefer the tailshaft centerline to be above the pinion centerline. This is not always easily attainable when running a raked chassis, and is compounded when running the "big and little" tire combos..

Back to your original question.... I do not like a pinion up angle at all....Guess maybe if someone could convince me that it is advantageous to handling, launch, or ride I might go for it. But, IMO and in my experience, a pinion angle of 2 to 3 degrees down at ride height works great....

The main thing is, as Mooneyes brought up, the driveshaft angle from the trans to the pinion should be down. U-Joints do no operate correctly or last long with a "flat" driveshaft.....