If you want to get a good baseline of restriction etc,pick a dyno in a 'clean' shop, take off the filter ,insert a straight open rubber tube(vary the length between pulls)....that will give you a better baseline than playing musical filters.....
V6 MTX 'Don't p**s up my back then tell me it's raining!!!" 'Its only nuts & bolts!' 'If I build it,fix it,upgrade it or modify it...MAYBE they will come....! Haines Motor Sports Inc, Dealer for 'Quaife America' & 'Autotech Sport Tuning' SOLE USA Dealer for the American Axle 'AUSSIE BAR'... Get a Turbo for you Zetec from HMS Inc...by 'The Demon' ...www.DemonDynamics.co.uk ..don't talk about it DO IT !!!