2004 C5 Coupe

This weekend I:
- swapped out the factory LS6 intake for a FAST 92 intake
- 1997/1998 return fuel rail
- drilled/installed an ECS Fuel Tank Bulkhead (8AN supply/6AN return version)
- hooked up the factory 5/16" return line off of a 1997/1998 C5 (I installed this almost a year ago when I did my headers)

Here's my thoughts/experiences:

Fuel system:
- The 1997/1998 fuel line is a direct fit and just clips right into the supports. GM did the smart thing and didn't redesign anything when they dropped the return line in 1999. They just deleted the return and kept using the same feed and mounts. The return isn't hard to route with everything in the car, it just takes some patience.
- The ECS fuel bulkhead is very nice and does the job, but it is a PAIN to get installed (still easier than dropping the tank). You have to fish the backing/retainer plate over the feed sock and that's not easy. Took me a good 30-45mins to develop that skill.
- The soft line from the 5/16" return hard line to the ECS bulkhead can't follow the factory soft feed (which goes up through a cavity in the frame) and instead has to drop down between the exhaust and the frame. There's plenty of room and it is in no danger of getting burned, but I put some DEI heat sleeve (picked up at local hot rod store) to both keep it cool and prevent any chafing of the rubber line.

FAST 92:
- I already had a LS2 90mm TB on my LS6 (using an adapter spacer) so the wiring was already done. When I did the wiring, I cut the factory C5 TB plugs off a rewired it using the LS2 TB plug to avoid using an adapter. This isn't hard but takes a lot of time.
- The FAST 92 does not have the MAP retention clip on it (I can't understand why they skipped this). You would think they would have at least put bolt hole to clamp the MAP down but again, can't understand why they didn't. Very disappointing.
- It is a KNOWN issue that the MAP can/does hit the cowl. Most people end of grinding the MAP to clear but considering the above issue, I decided to relocate the MAP to where the EGR was on the F-bodies (behind the TB on top of the neck). To pull this off, I purchased 2 parts off ebay. One is an aluminum EGR blockoff plug and the other was a MAP hold down clamp for a FAST XRT manifold. I dilled the center of the EGR blockoff plug to accept the MAP and then used this hole as a pilot to drill through the neck of the intake manifold. Then I put the MAP in the blockoff plug and drilled the hole for the MAP clamp.
- With the MAP relocated, I was left with the original MAP hole. I went to the hardware store and found a rubber "well nut" (looks like a rubber cork with a bass threaded nut). I put a long bolt up from the bottom, a washer and nut on the top, and as I tightened the nut down the rubber ballooned and wedged it in the hole. Nice and secure but no permanent damage/modification to the intake.
- The EVAP bung (behind the TB) is at a different angle than the LS6 intake. This makes the EVAP line bend and puts load on the bung (which is plastic on the FAST vs brass on the LS6). To take the load off, I used my heat gun to slowly warm the plastic EVAP line and then mold it to the correct shape (a slightly tighter turn).
- You need to replace the bolts in the valley cover with button head socket screws as the factory bolt heads will hit the bottom of the FAST intake.

I think that's everything. I'll take some pictures later. I now have a full return system with a (not currently operating) manifold referenced fuel pressure regulator, as well as the ability to add a booster pump if I ever need it. I still have to drop the fuel tank some day and disable the in-tank pressure regulator, but that's not a job I'm looking forward to doing (I'll probably collect up the parts and do that in conjunction with a clutch swap).