A fuel pressure gauge or sending unit goes into the "send" line into the fuel rail.
See my Info Forum write-up: http://www.clubb5.com/forums/viewtopic.php?t=63042. The picture there shows exactly how I mounted the Cartech as well as the fuel pressure sending unit.
If you want to see the fuel pressure in the cockpit as you drive, I highly recommend the Nordskog "Street Series" gauges. Digital, with a high/low pressure memory, sending unit is about $50, gauge is about $50, lifetime warranty, great customer service.
See my Info Forum write-up: http://www.clubb5.com/forums/viewtopic.php?t=63042. The picture there shows exactly how I mounted the Cartech as well as the fuel pressure sending unit.
If you want to see the fuel pressure in the cockpit as you drive, I highly recommend the Nordskog "Street Series" gauges. Digital, with a high/low pressure memory, sending unit is about $50, gauge is about $50, lifetime warranty, great customer service.