[Phantom]

I also mod for power and should be adding 30-40hp after I fix the cracked motor mounts. The reason that I'm adding power is I love working on things and I will be removing a few restrictions when doing it.

My mods for the Bonneville are to be L67 TB (from supercharged version) this will remove the pumping loss from going from a 3" pipe to a 2.5" then to a 2.5x3.2" opening will now be 3" all the way to the intake. This will give me a bit better throttle response so I will not need to press the gas as much.

Then I am going with the revised upper intake that will replace the mating 2.5x3.2" opening that goes back to 3" with a 3" that has a slight taper to increase velocity and even out cylinder filling. I will be cleaning the lower intake runners at this time for smoother flow and reduced fuel pooling this also smooths acceleration.

The last thing I will be doing that adds power is replacing the upper runners this one is where most of the power is coming from but the good thing is the power is mostly added at 2500rpm and up and the lower rpm looses a little power due to a small drop in VE below 1700rpm. So as long as I stay under 80mph highway mpg should stay the same and under 68mph it should go up slightly due to the slower cylinder filling at that rpm.

My Grand Prix has this setup except for the intake runners and shorter gearing and both cars have achieved a best tank at 29.2mpg hw at 75mph in hilly areas and this is with out any aero mods.