Well we sort of got our R/C feet wet at Showtime together.
Paris site says you can actually fine tune performance characteristics with the length of pressure line
A 2" difference in length can be felt by an experienced racer.
A short line will run out of fuel more quickly.
A LONG line will hold more bubbles that will stall your engine.
There is NO EXACT length for any given Car/Engine combination.
All that Boomer and I are trying to do is give everyone a starting point. From there, experiment and see what works best for your application.