According to the manual the ratios for the current Plus 4 and 4/4 are:
Gear Ratios. Plus 4. 4/4
1st. 3.87. 3.136
2nd. 2.08. 1.888
3rd. 1.36. 1.330
4th. 1.00. 1.00
5th. 0.76. 0.814
Final Drive Ratio. 3.73:1. 3.73:1
Both use the Mazda MX5 gearbox. We are now getting way beyond my technical comfort zone so please note that these figures have been directly copied from the latest user manual and any comments or inference of the validity of these figures need to come from someone who actually knows what they are talking about, in other words not me!