Hi, yup 1.9 is the better choice I think.
Soon after the release of the 008 XRAY shipped a conversion kit to change from 2.375 to 1.77.
However, subsequently all the XRAY drivers I know (only a small %!) migrated to 1.9 and that was before the advent of software controlled variable timing speedos which for STOCK motors dictate a substantially lower gearing and an IR like 1.9 and above. The T3 series ships with 1.9
I do not drive mod so please take the following with a pinch of salt. Before the new speedos I would tend to start my 10.5 wind FDR around 5.5 on a new track and work downwards to 5.0-4.6. So I am thinking that for you a starting point in the region of 6.5 is probably OK.
Hopefully someone with mod experience will comment.
I run 13.5 with an FDR circa 7.2. I achieve this with 1.9 IR 86/23. If you like that is because I am lazy; I achieve my 10.5 8.17 FDR with 86/20. I never change spurs unless forced to
![Cool 8)](./images/smilies/icon_cool.gif)
(that is not a recommendation)
I cannot advise on 64dp, never used it.
You can certainly get to the gearing region you need with 48dp and your 87 spur. If you have nothing in your spares box and are starting from scratch then I would buy an 85 spur. If you check the gear chart you will see that these two spurs will allow you adjust the FDR in steps of about .15. IMHO you will not need finer adjustment.
I suspect you will need to get another, say 2, bigger pinions. Probably best waiting to see what comments you get form the mod guys. Your current FDR is 7.51 which may well be a bit low (target may be in the 6s) but probably OK for you to go out and have some fun – if the rear wheels can hold the power going through that gear ratio.
Sorry if I am preaching to the converted but I have no idea what state your tyres are in. Those 4 little patches of rubber make more difference than anything in terms of grip. So at some stage treat yourself to a new set of tyres and compare the difference. With mod you will need hard tyres, I run my 10.5 with 32R so I suspect you will want at least 36R in the summer, otherwise I am sure you will find the wear rate draconian.
And in all the above there is no right way; it is what suits you, what is in your spares box and the size of your your wallet
![Wink :wink:](./images/smilies/icon_wink.gif)