well you can get 300whp with a ct26 and supporting mods pretty easily. You should just get your turbo rebuilt, hell with an upgraded ct26 there is more room to grow. Here is a direct quote from the info/reference section, it will give you an idea of what is possible with an upgraded CT:
As I know some, people don't venture into all sections; there was a thread in the technical section about CT upgrades. And since no one had responded I replied with what knowledge I have gained from countless hours researching the CT upgrades:
50 trim: Said to be most reliable all though I have never heard of anyone getting this one... I would think it isn't much bigger then stock there fore flowing around 350hp @ 18-20 lbs
53 trim: Slightly larger than above, at same boost levels probably 360-380
57 trim: Again, slightly larger than the above, and @ same boost levels 380-400 probably?
60 trim: Some people say anything bigger than 60 trim cuts turbo life down drastically, 60 trim on compressor graphs shows that is flows way more than any of the other 'trim' compressors. Should flow about 400-430 @ above mentioned boost levels.
60-1: Is a compressor wheel from a to4e something or other and many say to big for the stock ct shaft, flows very well though @ about 450 HP...
62-1: is a compressor wheel from another to4d or something turbo, again many say not very reliable. Should flow to about 470ish HP...
Also, what happens when your turbo is upgraded is they bore the inlet compressor housing out and put in a bigger wheel, on the same small shaft, which is why they seem to break easier with the bigger wheel; since bigger = more weight.
One other thing to think about is Clipping, which is the procedure to cut the exhaust fins @ a certain degree to enhance air flow for more top end flow; however I do not think this is a way to enhance the 'reliability' of your CT upgrade, as people say it is not a cut and go, since they can not measure precisely the angle for each fin.
Disclaimer:
This is info is solely based on information gathered from reading countless posts on upgrading the CT26. I in no way will garauntee you will hit those HP figure; as I don't know what mods you have on your car and have not tested any of them myself.