Looking for only the Some much needed help from you gurus on this one!!

Trying to figure why 2 cars with similiar modifications have such a difference in boost. I will say the car in blue is a top swap on a GT while the car in red is a GTP.


My GTP Has new Wires beldon and plugs (104) thermo (180) SSAUTO Headers, Straight Pipe no cat? cleaned the MAF BBV is good, New fuel filter. No misfires..

Both cars have:

Headers, FWI, 3.4 Pulley. Long blocks are totally stock. We have about 13 degrees with the top swap car that has more compression and only 7 degrees of timing due to KR with the GTP. Trying to figure out why I have a 2 psi difference at 6K rpm's using the same pulley. For now we are going to do a 3.6 pulley and lower the boost on the GTP. Hopefully it will take some timing then. A/F's are both 11.5 on both cars.
A link to the DYNO is attached.


Note: There are no cats on the GTP. The top swap car still has a cat.

The I am sure the hp difference is because of the timing difference.

What could caust the High boost and KR on My GTP?

Please advise.

I would start by checking the MAPS on both engines and see what the readings are.
Check the MAF readings too [maybe clean them].
If you see any disparity between the two,swap them from engine to engine and see if the problem changes cars.

_________________
2005 GT owner [Non S/C] with a "big DIC".
Two years later and I still love the car.
Thanks Pontiac...Bleen is keen!

Thanks OFFLINE, I am the owner of the gtp, I will take that into consideration..I was also informed that it is. A air exit issue like the him restricting airflow or maybe a loose timing chain. What do you think?