I started with a 10 oz tank and had to remove it a couple years later to replace the internal lines. I cut the tank to get it out and replaced it with an 8 oz. I still get at least 10 minutes of run time. One thing I have noticed about smaller tanks- the run time is shorter, but the engine runs more consistent from full to empty.
I try to get the tank at the correct height in relation to the spraybar. Drill the holes so the fuel line has a straight shot to and through the firewall.
Have fun with it, MIkeB