When I fitted Dakar Highs to my TTR I turned the the throttle body round 180 degrees so that the cables run on the underside of the bars. Thus you don't need to change the throttle cables. I've had it like this for a couple of years now and it works just fine.
Venhill came up trumps and I got my longer (+15cms - or 6") clutch and throttle cables back today.
I still had the Dakar High bars that I had offered for sale so decided to upgrade the standard steel bars on my spare TTR.
I swapped the bars and refitted the levers, throttle and hand guards along with the new cables and everything fitted fine. There is still enough length on the cables to fit 2" bar risers if that is what you need - and I know someone that has that combination
As a blatant positive review, I'd just add that mine arrived today and the quality is really good. I wasn't worried from Venhill but they are probably better than the OE ones and have all the boots and locating bits. The levers are very good quality too.
Another positive review here - I fitted mine this morning, the cables are excellent quality and even I managed to fit them without any problems! As a result the bike feels way better when stood up now, a well worthwhile mod if you are tall.