I'm looking into adding 2 electric fuel pressure gauges to the dash for my 502 EFI's and I have 2 questions:
What is a good cost effective fuel pressure gauge and sender?
Where is a good place to add the sender? if you can't attach it to the front shrader valve.....
Thanks.

You really can't go wrong with Livorsi gauges. They are standard equipment in a large number of new boats. You can remove the schraeder valve and put the sender in it's place. That port in the rail is 1/4" NPT and the sender will be 1/8" NPT, so you will need to use a bushing. You will probably also need a 90* street ell to turn the sender sideways. The other option is to remotely mount the sender and run a hose to it from the fuel rail.
Eddie

What kind of bushing? Does the livorsi come with the sending unit?

I use the Livorsi gauges as well, you have to purchase the sender and gauge to match the fuel pressure you are running EFI vs carb

Bushing =

Ok thanks.... I'll look them up online or does anybody have the part number for the sender and gauge for EFI system

just go to their website, the EFI runs much higher pressure and shows matching sender...or give them a call...

Lol, that's a coupler/collar.

This is a bushing-

Well then he needs a coupler. He has to adapt male 1/4" NPT (fuel rail) to male 1/8" NPT (pressure sensor). So the coupler has to have both female ends

6 in one, 1/2 dozen in the other. Witch one has more? LOL