My HP kit has the 38mm wg. I have noticed some boost creap when I was starting out with the kit. Now I have the boost set at 15#s and it does not move.
An interesting side note to this I will be stepping up this summer to a 351 and a t76gts turbo. My kit will only work with a 302 so I had to buy the 351 specific passenger side manifold and crossover tube. I was planning on just running two 38mm WGs because they are much cheaper than the big WGs. When I ordered my 351 specific pipes I mentioned that I wanted them to add a extra WG mount they said that I would be fine with the one 38mm WG. There reasoning was the higher boost levels I planned on running, 15 to 20#s. It will be interesting to see if they are right. If not I will have to weld on that nice shinny ceramic coated crossover pipe.
1979 Mustang coupe, EFI 393, A/A intercooled Eaton m122, 4r70w trans, Megasquirt II, T-top swapped in.
1990 Mustang, 545 BBF, C-4 with brake, ladder bars, tunnel ram with two Predator carbs, solid roller cam, 9", 390/45r15 drag radials.