I have one on a 340. Its running on an engine stand but wont go in the car for a while. All I can say is it starts instantly and sounds VERY strong. I bumped it the other day when it was 30° outside and it fired right up....amazing.
I dont think there is any real HP gains over a carb. The difference is with a carb you have to tune and tweak where the FI is self tweaking.So really I guess there could be HP gains if your not a good carb tuner. I hate fiddling with carbs so the FI was right up my alley.
So far I am 100 percent happy with it and so glad I went this route. It really is simple to install. Btw, I went with the Aeromotive fuel pump assembly since it seems to be what everyone recommends. Easy installation on that as well.
Im just running mech advance on mine right now. Once I get it in the car I will lock out my distributor and let the msd control the timing. Since I was breaking in a new engine I did not want to add another variable to the mix.
