Def not Toyomoto work. Toyomoto turns out a car with a minimum of 8psi.If hes only runnin 5 psi than it may be one a the couple shippable turbo kits that run that low of a psi and he may not have the uprgraded headgasket . Heres a detailed desciption of just their stage 1: Sorry for jumping into this all just interested as their are not many other turbo is300's other than myself and Hector round here.....

1) TO4E Turbo
2) Cast Iron Manifold
3) Turbo Piping
4) Wastegate
5) Wastegate Piping
6) Large Intercooler
7) Intercooler Piping
Blow Off Valve
9) Toyomoto Headgasket
10) Haltek E6K
11) MSD DIS 4
12) 550cc Injectors
13) Toyomoto Stage 1 ½ FPR*
14) Braided Oil Lines
15) Transmission Valve Body

Total (labor included): $10,500.00

Thats full stand alone fuel(Haltek) and the upgraded headgasket you need to run over 1 bar of boost and does 8-17psi....As well that Lance puts in a blitz boost controller with ALL kits...So I dont think its Toyomoto's work as all their cars come out with mad power...And 5 psi would be an embaressment to them haha....
Any pics of the car?.....He wanna run?
-Matt