Originally Posted by phunk

7/64 sounds large-ish to me for just the Walbro 255. If I found myself in your position, the first thing I would try is entirely removing the black Venturi from the bottom of the canister and reassembling (temporary). This way you can find out if there is any end in sight or if you might go larger until the component is entirely useless just to find it still didn't fix your fuel pressure spike. To take the part out completely will defeat the Venturi system but it will also answer a question, whether any size modification at all could even resolve your condition.

The idle pressure spike generally is only at idle and flattens out immediately when the throttle is touched, so I'm thinking your fuel pressure spike might not be coming from the Venturi system.

If you drilled out and it got you down a few psi, and then you drilled it a little more and it didn't go down more, than I don't think it's going to go down any more. It's a very sensitive setup and the slightest enlargement should have a measurable effect.

I suspect your stock fuel pressure regulator is backing up the return flow itself. But even in that case pressure should drop as soon as you touch the throttle. Which would lead me to consider the gauge is reading incorrectly or the regulator itself is regulating incorrectly.

Originally Posted by redondoaveb

You've got a twin turbo sound system, I think you met your audio goals.