Trying to decide on gear ratio of 89 Mustang 2.3 turbo c-4 intercooled. Still has original 3.73 gears. Approx 3000 rpm at 55 to 60. needest to say not good on gas. This is daily driver for wife. Tire size p225/60r15. Shifting is between 3300 to 3700rpm. The way I read I need to stay under 3000 to stay out of when computer changes loop modes. Don't want to do this several times. Have done several search but most comments are for 5 speed or dragracing with a c-4. What do you recommend.