Joekd - good job! I have the honor of having the 3rd real live Lister ever made, and the 1st with the updated tubing. You will notice a dramatic sound change at WOT. At idle and "normal" driving it sounds 100% stock, but put your boot in it and it sounds like an old 4 barrel carb until you get to about 3500 to 4000 rpm, THEN it sounds like it is sucking the filter through the tubing, you can really hear the air moving! So if you hear the sound change, it is only the manifold plumbing changing from the long to short runners, or is it short to long?