agreed... the 4:77 (s2000?????) and/or 4:88 are way too much for a 1.8. my car uses a 4:30 that's good at MOST tracks.
the biggest thing you need to consider is just how much extra gear you need out of a given corner. for example my 4:30 works fine for exiting most corners. i never find myself shifting in awkward places yet some tracks i could use a BIT steeper gear but in only one corner or two. is the change worth it? to go to a 4:44 would make sense but to jump to a 4:88 is a day and night difference.
most guys who used to run rotarys make the assumption that you use as steep of a gear as possible, since you'll be revving the ever living daylights out of the motor. not in a 1.8 miata.
suggestion. try a 4:30. since last year of using the 4:10 i've noticed a big difference and since it's an oem ratio in the 99+ cars, you can get center sections all ready set up with the torsen limited slip.
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