Grant - Each person has to assess the risk they want, of course. You can *easily* surpass the capability of the stock fuel system with a 60mm turbo just by raising the boost. I dyno'd 480+RWHP at 17.5PSI needing a little bit more fuel (no controller), and at 24PSI all indications were there for a 540+RWHP run before we let off at 4200RPM because it was at 14:1 and going leaner... There's a reason
[email protected] will tell you not to run an SP63 on the stock fuel system, and that's because you have to be way too careful to do so. At 18PSI, an SP63 .70 can be pushing 510+RWHP, enough to surpass the stock fuel system in a moment if it's not very carefully dialed in on race gas.
And a T78/T88 kit won't save you that much over a PHR/SP kit in the long run. There's a reason both PHR and SP include higher quality parts...
Fledis - True, but again, it depends on what you're looking for. You're never going to find 600RWHP on pump gas at low boost on any turbo, so if that's your target, I'd get a medium sized turbo that will make 650+ and stay with it. This of course will depend on each individual person. To me, though, if you have something like a T88 or HKS Twins and never tune them to push more than 650+RWHP (which I've seen happen a number of times), then what's the point?
Done right, though, yeah, a T88 can really shine...
-Pete