Yep, but what was he making with the exact same setup and boost levels with the GT3040? Was it a bolt on comparison using the same size turbine housing? Dont get me wrong all cars are different and things such as intake and cams will make a difference, but in the lower boost levels there wont be much between these turbos. A friend in NZ advised me the following when he did his back to back dyno comparison which confirms similar:
"Here is the big one: Based on tuning my car today, I can say that switching from a 0.82 GT3040 to a 0.82 GT3540 will NOT gain you any more than a few (~3) kw at the boost levels run on pump fuel. (22.5psi)
It does however only loose about 250rpm of boost threshold, instead of the 500+ I expected. I was a bit disappointed, expected about 30kw more power. I'd imagine the gains would be at high boost levels, (28psi+) where there would be more of a difference in turbine inlet pressure, but that is race fuel territory. I'm actually starting to believe that if only pump fuel is to ever be run, a GT3076 (AKA GT3037, GT30R) will make 90% of the power a GT3540 will but with a much wider powerband."
His GT3040R produced 316kw (425 HP) ATW at 22psi on 98 octane, and made useable boost from about 3500rpm, and full boost (22psi) hit at about 4500rpm. At 14psi it made 250kw atw, at 18psi 285kw, and 21psi 305kw. All on 98 octane and a conservative state of tune. He is using Kelford 272 billet intake and 264 billet exhaust with mild dial-in (both 2 deg advanced). He said off-boost torque was almost same as stock and max power was at 7700rpm - and thats with the stock intake manifold.
Its good to see real life comparisons like this with the type of mods people use as it helps paint a better picture overall of the type of power you get with the type of mods you make. If your mate has a lot more mods or ran higher boost levels then 23psi on 98 pump then you would expect a bigger figure from the GT35R. The GT3040 mainly has problems with compressor surge if someone is using a 0.64 turbine housing so use of a 0.82 or bigger is recommended with them.