[Omarius Maximus]

Problems with Ka-t: 1. fabrication(bypass this with greddy, some other turbo kit or ssautogay bottommount and downpipe setup with cheapo intercooler) otherwise, it's big money.
2. tuning: Hassle free-jwt ecu, enthalpy ecu, cheap but hassle cause of dyno time-safc, the best way-AEM (but its a big investment and you might as well get a wide band if your spending that kind of cash, or downtime because of dyno must be taken into consideration.)
3. Reliability: There have been plenty of people putting up big numbers on stock kas. But they are walking a fine line and they know it. Its one thing to run a stock ka well over 300rwhp for a dyno run, and it's another to do it for long periods of time at the track.

Problems with SR: 1. Not legal: this is especially an issue for people in socal cause the fuzz know whats up.
2.Its not that fast: Even with bolt ons, you'll still be hovering in the low 200s.
3. If you want more power, then you'll go through the same obstacles Ka guys have to go through, both on the hardware and software side of the engine. This of course throws the whole "reliable factory turbo" argument out the window. Also its a lot of time and money spent. not so much fabrication though.

Those are all the weaknesses I could think of, so choose whichever one puts you off the least. For me, they are both equal. With the ka-t, I'd always be nervously monitering the AFRs hoping nothing catastrophic would happen. With the SR, I'd always be nervously monitering the streets making sure that the fuzz don't pop my hood.
I think stock ka with electric fans and JWT cams is fun to drive, especially when you have full suspension and Yokohama A048s, maybe when I'm rich I'll get a turbo powerplant.