If you're serious about this car and modding it you should consider the following:
First and foremost, Determine if you're car is car is healthy and in excellent running order.
If you need to repair anything or feel that something is not up to par, fix that before modding your car.
Now, you have a nice reliable, running, driving car and it is time to mod it. The upgraded CT-26 is not going to give you any noticeable horsepower benefits at a stock level. Replacing the exhaust with a full (catless) free flowing system, Intake filter, better intercooler/hardpipes and a boost controller.
With personal experience (a Full 3" system, no cats) this along with the intake and boost controller, completely different car! Woke up and ran incredibly smooth strong. Do this mod.
The next step would be fuel upgrades and a SAFC to control and moniter whats going on.
I would recommend the lex/550s mod, with a bigger pump and an afpr, this tuned properly can make mid to high 300rwhp and still run and drive like stock.