I mean the difference in the amount of volume that flows through a -4an line vs a -3an line at the same pressure will be easily noticed, even with the restrictor. .25" ID vs .18", .0491" flow area vs .0254", 93% larger cross sectional flow area. I hope i did that math right.


Everything I read on honda forums with t3s is dont run a -4an line without a restrictor. You never need more than 25-30psi, something like that, but we can easily produce over 90. Heck a ton of them run a ball-valve and just keep clamping it down until the smoke goes away. I figured I'd play it safe and try a .040" if it helps, I'll braze my .060" and drill it to .050" and try that.