ITT you may discuss the need for a dual feed fuel rail
 

I'd love to save some cash on fittings and do a single-feed style rail with my M-tuned rail. Do I really need to feed from both sides?

These pics suggest that #2 and #3 were hotter, I'm not sure if it's a coincidence considering the feeds are near # 1 and #2:
https://lh3.googleusercontent.com/-3...0/IMAG0084.jpg
https://lh6.googleusercontent.com/-U...0/IMAG0085.jpg
https://lh4.googleusercontent.com/-R...0/IMAG0086.jpg
[/img]https://lh5.googleusercontent.com/-eoJrLZZF5rU/TpbgfG3zefI/AAAAAAAAAds/UnYvGJtCU7o/s800/IMAG0087.jpg[/img]
What do you gays think?

Been proven time and time again that there's no difference

You may now explain the uneven cylinder temps.

the problem i see is making the assumption that under the boost, those cylinders are running hotter. what you're looking at is the evidence of what was happening while cruising at low load for hours, weeks, months, because, that is mainly what you do. to be able to tell what was happening under a heavy load, you would have to start with scrubbed clean combustion chamber valves, pistons, plugs, etc.... then start it, run the track hard and cut it off as you pulled in the pits. then pop the head off and have a look see. it could be said that if it's happening while cruising (leaner in 2&3) it's probably the same under load, but that's just not always the case. the flow of fuel and air @ 15psi wot in 4th, is drastically different than at 15% throttle, in vacuum, cruising in 6th

it'd be nice to have if your made of money, but i don't believe it's necessary at your planned power levels.

What about intake manifold or cylinder head flow being uneven?

Nope.

That ^

corollary discussion:

what are the benefits of an aftermarket fuel rail besides lighter wallet?

It looks cool. Impresses the hell out of ignorant people.

+1 thats about it

Fuel delivery UP TO a certain cylinders' injector is not the only variable affecting uneven temperatures. Hell it could even be the injectors themselves flowing a tad less in #2 and #3.
Its all assumptions.

It also fits on a 99 engine with a stock FPR and was readily available.

(Posting from my phone.)

Tom @ ffs likes dual feed. Nuff said.,

not sure you can even see mine in the car.

Larger bore = more fuel volume available = less localized pressure drop as each injector fires.

When Tim built me my .500"ID stainless rail, we were less worried about dual feed and more worried about making the ID as big as possible.

If I ever redo fuel lines, I will probably cap my 2nd feed and just do a single feed/return.

Mine came with the SC package I bought. Will I use it? Sure. I have it, might as well put it on when I do the injectors. But if I didn't already have it, I'm now convinced that it really isn't necessary.

Cool, I'll save a lot of money. Not enough for an AFPR from Fuel Lab, but enough to take your slore girlfriends out to my apartment and watch them clean my penthouse apartment.

I think everyone is looking at this the wrong way. Cylinder heat is a function of the heat generated and the heat dissipated. It seems unlikely that fueling is causing any real difference in cylinder temps, so could it be heat rejection differences? I assume you have rerouted the coolant flow, and put in a properly beefy cooling system? In essence, why would those cylinders reject less heat than the others?

What about the headgasket/coolant reroute complifucked issue? Where sometimes a reroute was good and sometimes it wasn't?

Are you talking about the NB head gaskets? Where Mazda reduced the size of some of the coolant holes to balance the cooling of the head despite the imbalanced cooling of the block?