Fuel Pressure Regulator Rising Rate or not?
 

just want to no if they worth paying that bit more for any advise would be great thanks

compared to what? are you refering to a 1:1 rise or like a 1:3 rise? two very different versions. the 1:1 is a must for a boosted engine your stock regulator is this. the 1:X style was a long time past way to 'enrich' fuel flow for a boosted engines in the early days which should be discarded asap as the 1:1 with programable fuel injection ECU's gives indefinatly better control.

z

1:1 isn't a rising rate, its direct reference. The rate of fuel pressure rise has to be greater that the rate of manifold pressure reference to be a rising rate.

Rising rate regulators are still used quite a bit with supercharger kits, in the 8:1-12:1 range, typically called FMU's. The problem with them is the amount they increase the fuel pressure... at 40 psi base, 10 psi of boost with an 8:1 FMU, your line pressure is going to be 120 psi! This lowers fuel pump flow output, decreases fuel injector spray quality, and puts a lot more strain on the fuel system seals.

There is very little use for a RRFPR on a car with a tunable ECU. There are too many drawbacks too them, and really only compensate for injectors sized too small.