New Belts

lots of the 1000 and 1100 ds motors need the belts run loose to stop them being noisy when hot, which I believe is the bearing surface of the cam rubbing through the oil film. it's a nasty bearing running style noise that really makes your skin crawl. mainly happens on the later motors, 2006 ish production, with the different lh journal. don't think I've heard it on an early motor.

some of them (all models) do whine a bit when new, but I don't see that as an issue. the problem you run into when supplying an aftermarket part of such perceived importance to the general public is that you have no control over what the general public does with them. quite a % of the general public tend to do things that make professionals in the appropriate field gasp in horror. so if the result of fitting the exactfit belts are not the same as the genuine in some way when fitted by someone who's skill level is unknown and unobserved, the best thing chris can do is offer a refund and recommend oem, as that way you avoid any issue based on the product and potential misuse of it. the public in question may be doing it right, but when the problem is 1,000km away and you can't see what is being done you have doubt in the process as such.

the recommended belt tensions have varied a lot since the sonic method was introduced. originally they were 125/140 ish or 140 on both, now they're saying 110 and 90 when checked in service. and the difference b/w 100 and 180 on a 2v is only a minor adjustment because there's no easy incremental adjustment system like a 4v. 4v is quite easy to hit a number, 2v is back and forth.

just my take on it anyway.