During Sxth Elements elantra sport m/t shop car build they said the stock fuel system starting having issues at around 320whp. Then they added a aem methanol kit and just dyno'd 393whp 320wtq. Lap3 has a few DCT with 300-320whp. These horsepower numbers are with their upgraded turbo kits, the factory turbo is good for up to 240whp.
From technical documentation, the D7UF1 that these cars have (the higher-torque DCT), is officially rated up to 250 lb-ft. See one of the sheets here This is also replicated in a few other places on the web.
That being said, there may be various anecdotes here and there of higher power numbers. The ECU tunes provided by SXTH, and others, ask you to specify manual or DCT when you order so the appropriate programming is given; the ECU CAN limit turbo output at lower RPMs, of, course to try and stay at a reasonable torque limit until you get higher in the powerband. The 1.6 engines are undersquare (77mm x 84.5mm; bore being smaller than stroke length) so they are naturally pretty damned torquey and shows when you cram higher boost pressure in, and how easy it is to hit 300 lb-ft on these engines just looking at them sideways. The 1.4L version of these engines are actually ever so slightly OVERsquare (77mm x 75mm) and would have much more balanced HP/TQ numbers across the rev range along with a higher powerband and rev limit. 1.4L max HP is at 6,300, 1.6 is 6,000; the 1.6 revs pretty freely but the longer stroke puts a hard limit on redline.
As an aside, I'm hoping the refreshed i30/EGT gets the wet clutch DCT across the board. But I have a feeling it'll be an N-model only transmission.
I do plan to get an ECU tune this Summer, but only with the spark plug swap, intake, and MAC BOV/Wastegate sensors. Nothing else. I never planned to modify the car heavily (it's a daily driver) or else I would have bought the manual. So I won't be pushing the limits of the DCT, and won't tempt fate as a test subject for torque limits. Besides which, I had to wait to rack up some mileage anyhow; in 9 months I've just passed 5,400mi on odometer. So it is barely broken in.