2003 VIII, 100% stock, 60k miles

My friend is having trouble while at 1/2 throttle to WOT. The car seems to buck or bog down when hitting about 12lbs of boost. It starts bucking from 4-6k and sometimes clears up by redline. He thought it had to do with the ignition system so he decided to replace everything. Coils, plugs, wires, CAS, clean the MAF, etc. His boost seems to be topping out around 14-16 psi.
Anyways, I think it has something to do with fuel, to me, it feels like fuel cut, when there is too much boost and not enough fuel. I was thinking possibly the regulator or the pump, but Im just guessing off the top of my head. I haven't tested the fuel pressure for him yet, but will be doing it Monday. FYI, there are no CEL's at all.
I was just wondering any input you guys have to help us out.
Thanks

 

needs to be tuned

 

Great, thanks for all the help...

The car is stock and will be staying stock. Plus the car would need to be fixed before it would ever get tuned.

 

boost leak. do a test I bet thats the problem

 

+1 beat me to it

 

+2 thats my guess for sure

 

Lol, thanks guys but I did it already too. I pressurized it up to 25psi and it held fine.

Any other suggestions?

 

The problem it tune related, the bogging is knock and the ecu pulling timing. If it was fuel it wouldnt go away after 6k it would get worse. Its easy to see if thats it log the car.

 

How would it be tune related? The car is 100% stock with no aftermarket tune. There is no knock, plus the car would be pulling a DTC if any of that would be happening. Theres no point in tuning the car when it was fine last week, you dont just randomly tune cars to hide the problems your having. You have to fix the current problems at hand then modify or tune it.

It usually bucks till red line, but sometimes its only from 4-6k.

 

Log it.

 

Whens the last time u changed ur oil. my car was doing this after not changing my oil for 10k miles. i changed it the other day and all of a sudden theres no lifter tick or bog anymore! lol

 

He changed his oil 1k ago. I feel sorry for your car, 10k miles between oil changes... wow.

 

well i kinda want my motor to blow so it gives me a reason to take it apart and put these parts inside of it !!