When I bought my car the previous owner gave me a dyno sheet. Mods include 5Zigen catback 3 inch zorst, 7 inch muffler, K&N air filter and thats it, and it was running 6/7psi (stock boost) and doing 153kw @ the wheels, dynoed at boostworx.
Now I'm running 14psi off a Garrett GT3076R, Turbosmart boost controller, turbo back 3 inch exhaust with hiflow magnaflow cat and the same K&N filter, no missfiring plugs (iridiums) gapped at 0.7mm. How much more power over the stock figure do you think I'm making? because I tell you now its ULTRA noticable.