Did my timing slip?

[dipstick]

Shortly after I bought my 97 2500 on 07/00, I installed a #11 plate, Walker muffler and Cat test pipe. When I first installed the plate in the stock position, it felt great for a couple of weeks. Then it seemed like it lost power. Still had much more power, but not the same. I then slid the plate to about 1/2 of full forward and again it had more power for a couple weeks. Almost to the point of slipping the clutch. I have the star wheel about 7 clicks in with the medium spring and the housing full forward. My boost is 38-39 and I can get the EGTs over 1400 on a WOT run in 4th. Don't have the same amount of black smoke either. Today I checked the boost fitting to the AFC housing and made sure the diaphram wasn't leaking. Did my timing slip and what caused it.

[mopartec]

a friend if mine says this does happen esspecaily if the nut that holds the pump to the drive gearhas come loose. pump has been worked on and has not been torqued just tighten. also have seen a lot of waste gate diaframs go bad on the turbo. you can replace the diaphan alone. at one time you had to replace the whole turbo to get the waste gate diapham.

[dipstick]

Don't know the history of the pump, but I don't think it has ever been touched. I have the set-screw on the boost elbow from TST screwed all the way in so my waste gate doesn't operated. I get 39 lbs boost at the most. I think I may get the timing kit and set it to 15° myself