This may be true, but considering that the whole exhaust was only 600 smackers, I think the value for money is there. It's probably been discussed before, and I am no engineer, but with my understanding of fluid dynamics, a single 3 inch system will still out-perform the standard twin 2.25 item anyway. I say this because I would assume that in conjunction with the greater 'wall to volume ratio', the centrifugal forces created when joining/leaving the twin setup from muffler/cat etc would greatly inhibit the efficiency of the standard system. Which lets face it, was just pulled off the v8s and put on our cars without a second thought. Regardless of that, many friends of mine with jap cars that make pretty serious power tend to use 3 inch exhausts themselves without any dramas. In their, and my opinion, it's really only when you are looking to make 600+ rwhp that 4inch will be a necessity. These cars are fun to drive in. Who knows I WIN? I agree with you in that I believe a 3.5 inch would be ideal for the ute, but as I said at the start, a bargain was there, so it was taken. The fact of the matter is that we're very happy with the power, and making 300kw at 11lb through an auto is nothing to sneer at. Not that I think you are though mate. Cheers for the advice.