Restriction In The Exhaust

[Lithium]

More boost will make a restricted system worse, if the rear housing or manifold is restricting the system more boost will dramatically increase manifold/back pressure coursing detonation

Get an EBC, they are better all round and will hold the wastegate shut longer by not allowing it to creep open which will make it ramp onto boost quicker and you can try different boost levels to better see what's going on

My thoughts too. If nothing else the tuner can TRY and hold a steady boost level to redline - if they try and hold 20psi and they run into flow issues or holding boost issues they SHOULD be able to build a bit of a picture of which area of the setup is starting to hold things back.

My feeling at this stage that you may be getting near the limit of this kind of combo and are probably already making decent power - though the bleed valve could be exasperating this. As I asked in PM, what discussions have you had with your tuner about it? They will have more of a perspective than any of us on how the setup is behaving... we're just taking pot shots from what you have shared.

[rondofj]

My tuner said that at 23psi it wasn't making any more power so they backed it off to 22psi on a safe but still optimal tune, recommended Type A Poncams for more power and an EBC to hold boost steady up top. EBC I will get, cams not, they didn't mention anything about exhaust manifold being restrictive or housing. Yavuz did say that with a bigger housing I could get more power but that's only after I asked, so not really recommended me one unless I really wanted to go that way. He said these Precisions will easily boost to 30psi with e85 and the right setup.

Edited May 15, 2014 by rondofj

[Lithium]

OK - the fact he recommended an EBC is a huge hint, if it's not holding the boost he wants and it's making respectable power for the boost it is running at peak power then that is a pretty big indicator I reckon. Holding more boost at higher rpm = holding more torque at higher rpm = more power

[rondofj]

Thanks mate, that is definitely on the cards now..