I ran 10 psi on my car for a long time until my oil feed line decided to dump all the oil in my engine out and threw 1# rod through the block. But felt good and had rc 310 injectors and FMU. Depends on what turbo really. I hate when people ask how much boost. cause if you have a T25 running 15 psi. is probalby the same as running 6 on a t3/t4e set up. so what do you have? Ask yourself that first. late