Shaun, here is what I do to check if the turbine is too much off center: I run the engine for about 3 minutes at full RPM on the first test run at the field. I then get the pipe out. If there is a zone that changes colour towards blue ( inner pipe ) , then the turbine is too much off centre. There is nothing scientific in there but I've sticked to this method for a long time and never got any issue, even with the very flimsy early FEJ pipes ( that I upgraded quickly BTW ).