I depends on how much you want to spend really. If $800 is in your budget and you want some track time I would say go for the SU145 because more adjustability is always better (I don't know how many of these are left so you may not be able to get them anyway). If on the other hand your budget is limited to $450 (I fall in this category) then go for the SU143's because they are an excellent shock for the price (I have the F bike equivalent to these, the HO140's, and I am very happy with them).
For reference, the SU143's are normally $800 give or take $50 depending on retailer, and the SU145's are normally around $1250, again give or take around $50.
So far I have not had a single complaint about the SU143's or the HO140's that I have sold - except for one guy that bought them for the wrong bike. So you really can't go wrong with the 143. About the only time that I would really recommend the 145 over the 143 is if you do vintage racing or track days on the bike - then I would say go for the 145 because you'd want the extra adjustability it offers.
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