I think I've isolated what is causing my hesitation problem. I did a boost leak test yesterday to find that my injectors are leaking at the seals where they go into the intake manifold. I'm running a v8 long runner JDM manifold with adapter plates to use USDM fuel rails. The injectors are Bosch 100cc and have all new O-rings on them. It seems that the adapter plate is about 1mm too thick which is spacing the injectors a little too far away and not pinching them into the manifold tight enough. 3 out of 4 injectors were leaking under the boost leak test at 7psi. I'm thinking that I'll just swap back to a USDM manifold and do a TGV delete. At least that way I'm confident I can get the injectors to seal.