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air/fuel ratio is spot on at 14 psi as i have an innovate wideband guage and 42lb injectors so how could it be a lean backfire? and if the turbo has a 1.00 bar actuator then one would think the turbo should be able to handle this boost.

turbo will quite happily do 30 psi on a 4 cylinder but on a six its overspinning thats why the power falls over its gone past where it moves its maximum flow of air and the blades are just cutting air making huge heat the backfire could even be a hot spot in the combustion chamber IE glowing plug and its ignited the incoming charge via the open inlet valve yous are just caining it for no real reason its stupid LOL

thanks for the diagnosis and it was just an exhaust manifold gasket making all the fuss.

Something you may want you read about boost and valve springs.
http://www.lindseyracing.com/LR/Parts/9 ... RINGS.html

hi ,
just a quick question on the fuel ratio now i have taken the manifold off and match ported everything and also ported the rear turbo housing i have now noticed when it receives positive pressure the wideband sits on 13.0 or round abouts instead of 12.

it obviously is breathing heaps better but is this ratio safe?

also found out why we could not get the boost under 14 psi the reason being the actuator is a 1.0 bar setup so i pissed that boost controller off.

doing all these things has solved the problem with that wall we could not pass as now it is fucking awesome to drive with no decrease in power all the way to the top and just wants to keep going but i back off before 14psi anyway.

will keep ya posted on how long it lasts, and thanks for all the advice people have given.

an afr of 13 is pretty lean for boost, i'd be aiming for 11/12's ....

You will need to adjust the VE table as it represents how much air flows in to the engine when a certain pressure is measured in the manifold. Since you've improved the flow, more air is getting in the for that same pressure.