Do you have one of the new kits with the air to water intercooler?

 

I don't think any porting/polishing type headwork is needed as 12psi will just blow the air in there regardless. A couple things you might want to consider for improved performance are: a free flowing muffler (e.g. Magnaflow) Stock cats and exhaust manifolds are OK. and a good cam such as a LPE gt2-3 with LS6 springs, but I would wait and see how you like the blower with the stock parts first. I'm not familiar with the KB systems. Do they use the stock intake manifold or supply their own? There is an uneven air distribution in the stock units that gives the no. 7 cylinder more air than the others, resulting in leanouts and possible detonation/damage on that cylinder. Something to maybe keep an eye on. Otherwise, as I mentioned before, everything should be fine as long as fueling is good, the IAT's are sane, and you don't go crazy with timing advances.

 

I would only run 9, maybe 10psi. You will need injectors, pump, good tune, etc...
At 12, IMO, you are on borrowed time.

 

I have no cats, two flow master muffler, long tube headers, 80mm throttle body, air to water intercooler

 

Hey, sorry to butt in, but what about 8psi on a LQ9? Do I absolutely need to replace my fuel pump to run that? I already have 42lb injectors.

 

Yes, you do. You may squeak by, but its cheap insurance.

 

Cant understand why, I'm running 9 PSI, with 42lb inj. and fuel pressure is always steady around 65psi ??

 

You need to buy my forged 4.8 internals

 

Speaking from experience. Replace the stock fuel pump before you loose your motor. It is alot cheaper than replacing the engine.