Your engine may be radical enough that a t-slot restriction will be helpful. It should help if its too rich as it transitions into the start of the mains.
Today I made the IFR smaller (maybe). Didn't make much noticeable difference!
I don't have the precision equipment to drill .033 instead of .034 with sufficient accuracy. Will increase the IAB slightly. If still too rich, then I'm going to make the TSR smaller.