The only extra weight is a couple rubber hoses and the regulator. The rail is aluminum which will be lighter than factory. I have plenty of weight to lose in other areas of the car.

The m-tuned aluminum rail weighs more than the stock aluminum rail. You're also missing the weight of the fittings, and hose clamps which all add up. The stock rail and the stock regulator are the lightest setup and will not make any less power than what you want to put in.

OE is more than enough, I know of someone with a 255 Walbro & OE regulator who is getting excess fuel pressure. You can get an OE replacement Bosch fuel pump for $62 on Amazon. I am thinking of replacing mine now as I am having an intermittent hiccup where I can hear the fuel pump relay reset(new-used one ordered too), car goes lean, and then it goes about it's business.

As an aside, I hit the dyno for one last number before I make the switch in a week. Car made 137whp/123tq on 91, however I did notice the duty cycle was showing ~73% near redline. I am starting to question if I need injectors, the most cost efficient would be re-manufactured RX-8 injectors from RockAuto ($130 a set). I may give it a shot without them at first, but it's something to keep my eyes on.

For those that are interested I took the plunge 2 days ago and made the change to E85. I ordered some GB Manufacturing RX-8 injectors from RockAuto. $155 shipped to my door and they are re-manufactured Denso. Swapped these in, made sure nothing leaked and ran the car nearly dry. Obligatory picture of injectors.
https://www.miataturbo.net/attachmen...ine=1388010749

After looking like a moron driving my car endlessly around my neighborhood with fuel jugs in the car I got the car nearly sputtering and shut it off. I filled with 5 gallons of E85 and it fired up. I altered my req fuel by changing the stoich number from 14.7 to 9.76 and everything worked fairly well. I got the car drivable and went straight to the E85 pump 5 minutes away and filled the tank up the rest of the way
https://www.miataturbo.net/attachmen...ine=1388010749

For the fuel map I left my AFR targets at 12.8 for my 100kpa rows and left my timing the same. I will be on a dyno within a week or two and from there I'll start playing with a leaner mixture and more timing. I have noticed I need to decrease the cranking pulse in the colder areas, it really sputters at first and doesn't always catch. I attached my map if you care to look at it, I've noticed the injectors are at about 57% duty cycle with the car as it is.