^What he means to say is that the AE86 came in two variations in the US. The SR5 and the GTS.
The SR5 is single-cam 4AC, carbed, rear drum brakes, and was available in automatic. Among others things. All around its only pushing around 70 hp give or take. Especially with the auto.
^This is what you have.
The GTS on the other hand is your initial D car and close to the opposite. Twin-cam 4AGE, fuel injected, disc brakes(sometimes even LSD), only available in 5 speed, not too mention it looks a lot better with the front lip and awesome seats. Probably pushes around 100 hp give or take.
Now most people will tell you, and I mean MOST people will tell you to just sell the sr5 and buy a gts or swap in a twincam(quite a bit of work but from most perspectives, worth it). Few have love for the single-cam.
Now, if you decide to keep your sr5. there is a website,
http://4ac-powered.forumotion.com/ That will hold most you need to know. the 5 speed swap is well worth it if you plan to keep the sr5 for a while, but sourcing the parts may be a hassle. If you plan to go twin-cam, dont bother swapping the sr5 to 5 speed as you will end up doing it with the twin-cam swap anyhow.
Like idream said, it comes down to your preferred choice in the end, keep what you have, swap it, sell and buy a gts, or try and build a 4AGE killer out of your 4AC.
