Ratios are a little different for sure for us here I've found provided how confident I am with the Regular gears, and how many front drivers I wish to drop when change to mini, If I feel last time out Regular were spot on and were only going to go 2 front driver sizes smaller, I don't even look at the ratios, I go 2 smaller on driver and remove 8 teeth from rear , and provided track condition is comparable that day to the day using regular gears it works out great, and yes usually a tenth faster on the mini's, especially to time trial with, then If I'm going 3 sizes smaller on front driver , I'll pull only 3 from rear for total of 11 less on rear than regular gears . I think for Jr 3 you only switch to Mini's on a track that making grip on a grip scale 1 to 10 at least a 6 for grip , and when you do figure a 48 rear gear and use whichever front driver keeps you with in 1 of the 48, meaning a 47 or a 49 If you Find yourself having to vary rear more than that adjust front driver by 1 more, and for sure it makes more of a difference to time trial, then on the flip side for Jr 3 with regular gears put a 58 on the rear and whichever size front driver keeps you on the 58, or again within 1 either way 57 or 59 and don't even worry about ratios.