Hi Guys
Once again many thanks for the further feedback. Obviously, the lean burn problem is related to the tuned pipe, which may or may not be optimised for the 53. After having been 'burnt' with this thing, I think that I would now rather look at the set-up from a properly engineered perspective, as a starting point. Does anybody out there know what the formulae for these things are, or where one can find it? Since I'm not in a position to re-manufacture the header and pipe, at least it should be possible to calculate the optimum length, which is now the only variable (other than fuel mix?)