Asumeing he builds a 408 stroker with a .70 overdrive. That motor if built to the same compression A/F ratio cam ect... It could potentially use less fuel than my motor is useing right now. It will only be makeing %70 of the strokes as mine at cruise. .70 X 408 = 285.6 cubic inches displaced every drive shaft rotation where mine displaces 323 cubic inches every driveshaft revolution. The only thing is he is going to build compromises into his combo that are different from mine for the sake of performance. His heads are bigger and will flow at a lower velocity than mine are flowing now. His cam will be more duration and overlap that will hurt efficency, he is also going to a lower gear ratio. I don't think his combo will get as good as mine is getting but if he keeps from he may not do to bad like low 20s.

As for the weight thing I think it makes more differance in town. My car the day I bought it we weighed it with a full tank of fuel and it weighed 3060. Since then I have added a 8.75 rear but removed weight via aluminum intake lighter Neon buckets and a mini starter from the front as well as lightening up the rotateing assy a few pounds. I think it is probably around 3100 pounds with a full tank now. It is also sitting a little lower to the ground now. I do think areo is part of the reason for the big drop from 65 to 75 mph. but not all of it.

The 300M can not run as lean as my motor because a lean mix will over heat the cat and make the NOX emmisions go up. I set my carb up with the smallest jets and biggest rods I could find and lowered the metering tree till it started to lean miss and then brought it back up a hair so I know it is cruising on the ragged edge of lean right now.

It is funny that the problems I expected to have are not being problems at all. No burnt valves no pinging it still makes good hp whenever I want it Just some stupid periphrial junk