Fuel Pump

The 255lph in your tank is a good start, but it probably won't be enough for a 150 shot. The key is to having your fuel system flow enough fuel volume. The stock intank pump or even a bigger one is sufficient for a 75 shot of nitrous or maybe even a 100 shot, but that may be pushing it a little. I run a 150hp shot and had to upgrade further than my 155lph intank pump, with the mods in my sig. At first the fuel pressure was not staying above the 80psi. or whatever the dry system boosts it up to, with just the 155lph in the tank. So the Hobbs fuel pressure safety switch would cut off the flow of nitrous. So I went out and bought an MSD in line pump and installed it and everything has been fine since. It's been a few years, but the one I bought...I believe was a 200gph pump. Similar to the old tried and true T-Rex inline fuel pump. The Rex would work as well or something that flows similar #s. I know your 255lph flows much more fuel than my 155...but I've read that other people have had to run an additional inline pump for nitrous even when running a 190lph. I couldn't say I'm 100% positive...but I thought even the 255lph was not enough for a 150 or higher shot. Good luck.