Fuel Pressure regulator

[filh]

Ok guys , I think you're both right and very experienced . I drive my car in rallies for three years now . My problem is as follow: I had a short rear gear ratio (5,3:1) which is very expensive but no reliable .It brokes after
about 3000km of race . With a stock engine , it's not very fair , but is very expensive ( cost in 2003 :1700€). So I bought a longer and cheaper one from Stageone ; 4,7:1. It's now hard to raise full revs in 5th gear.
And I find it hard at 6000 rpm to raise 7000 rpm. I suspect a fuel lack ( I'm running a KN like air intake)
I'm planning to change cams and injectors, but would like to keep the injection system as it's so reliable. I 'm realist and don't expect adding lots of CV .
In the past , I modified 2tg engines running carbs, but here I'm a bit lost with injection system. You often speak about Supra , but it's so rare here now.
Thanks again and all advices welcome .
Filh