Wrong info from me about the mining software. The Titan uses bfgminer v 5.0.0 so extranonce isn't an issue.
You will have to set #xnsub and #skipcbcheck manually, i.e., your pool url will be stratum+tcp://stratum.nicehash.com:3333/#xnsub#skipcbcheck .
Based on what the Westhash site recommends for difficulty I used 32768 which is the recommendation for a hashrate of 64MHs - 128MHs, although I'm over that at app 330-350 MH/s, but the 64 - 128 MH/s is the highest range on their chart.
Try to set the difficulty to 16384 - d=16384 . You can set the difficulty you like, you don't want to put the difficulty they recommended. If this is also not working, don't set any difficulty, just mine without difficulty parameter(d=X).
After 6 hours with that difficulty my hashrate is way lower than I get elsewhere (327 vs 340+ at clevermining) and rejects is at 6.8, so that difficulty isn't the answer.
I keep hearing (actually only from Nicehash/Westhash people) that the Titan works on Nicehash/Westhash and gets 350 MH/s with low rejects, etc but every time I try it I get lower hashrate and high rejects. I'll probably head back to clevermining - where my return might be very slightly less - but I can set the miner and forget it and get a high hashrate and low rejects.
Please do what I say and check whether it is okay!

-MZ
Thanks for the additional feedback. I've been using the #xnsub and #skipbccheck all along based on a posting/recommendation on the KNCMiner forum on 1/10/15 which said the following:
as "proof" but to me that looks like 320 MH/s over 1253 hours, not 350 and what looks like 0.00% rejects
.
Based on the screenshot, about an hour ago I tried 16384 and I'm currently at an effective hashrate of 327 MH/s with a reject rate of 6.5% so I still apparently haven't located the secret decoder combination of settings which will get me mining at app 340-350 with a reject rate of around 1-2%.