So it took an extra 1.3 liters to gain 1-2 mpg, not really much of a difference.
Torque by itself is meaningless. u could change torque output with gearing like the M5 does.
I'm new to the site and I was reading this trying to get some info on my mustang LS motor swap and came across this post. First of all Dave there is NO WAY you will change the torque output of a motor with gears. I figured i would throw this on here considering I am in school for high performance automotive technology. The only 2 things you will do with gears as far as horsepower or torque "output" of a motor is concerned is A: If you lighten up the rotating mass of the drivetrain you will reduce the power lost by the motor when turning the componets of the drivetrain. B: You can change the gearing to keep the motor inside the torque curve but you will never ADD or Change the torque output by changing the gearing. You will in fact only lessen the loss.
Also my buddy's car is running off a 90k replacement motor without anything being changed outside of the cam, gaskets and intake (to include throttle body etc) on 10lbs of boost, and has been daily driving/racing/murdering this car for 18 months now putting over 500 at the wheel. Yes anything can go wrong with motors at any mileage. There are trucks and cars of all makes and models coming into the dealership i work at part time that has blown/broken _________ after less than 10,000 miles. Yes putting go fast parts on ANYTHING will increase that risk however my old mustang had a 347 on 12lbs of boost and I ran that car at the dragstip everyweekend during race season and on the street for 3 years and never had to change anything outside of spark plugs and the fluids (got lucky). I helped build a c6 zo6 with 10k on the clock and it blew up on the dyno. I blew up a ford motor in 500 miles. The list goes on and on. So if you are happy putting less than 1,000 in a motor and you don't care about changing it since we are all car guys and like working on things bolt it in, blow it up, lather, rinse, repeat.