I converted my Monte to TPI years ago and this winter am going over alot of little things, alot for appearance and some for function. I removed the fuel lines under the hood to where they meet the stock feed & return lines, I had previously had high pressure rubber lines double clamped, no issues but plan to use compression fittings and black nylon braided hose or such for a cleaner install. My main question is the Monte (car was a LG4) has 3/8" feed and 1/4" return lines. Would 1/4" return hamper anything or cause issues? The car has had some issues over the years with driveability but when reading fuel pressure its been fine. Stock TPI fuel pump, nothing fancy as its a mild almost stock 350 setup. 4.3 TBI Monte cars had a 5/16" return line so my thinking is there must be a reason behind it. Since I am in the process of changing things around I'm tempted to replace the 1/4" line all the way back with 5/16" but then again if its not needed, I won't bother.

 

Anyone who has converted to TPI feel free to .

 

I have done a few G-bodys, I have always used the 5/16" line.
If the fuel pressure isn't up, it's probably ok.
By that I mean, pinching the return line would raise the pressure.