Um "MODS" means modification you idiots LOL.Those ARE modifications. It doesnt have to be a performance mod to count, just something you replace on your car that is better or looks better to you.Anyways I say 3.55s or 3.73s.Personally I am leaving 3.27s in my GT because I am getting around 23-24 MPG and I want to keep it that way.I have been through a series of gears in my 66, including 2.80s (factory) 3.00, 3.55s, and now 3.80s.3.80s are nice and made the car a little qicker but gas milage has dropped off quite a bit...now I tell you what makes it run is slapping on the 23.5 inch tall 205 555r nittos that I have up front on the back....WOW!!! but I did NOT like how undrivable it was and how much gas we used LOL.(the weigh alot less than the rears, so less rotational mass = more power to the tires) I will not go any lower than 3.80s in my 66, anything lower just gets on my nerves because the engines screaming and your only going like 50MPH LOL.Heck I cant stand driving around in 4th in my GT because all you hear is exhaust and just feels like you need to shift...luckly I can but the guys with the 4.10s cant....I couldnt stand it on for an every day driver.