Ive had an automatic and a manual as well, (the manuals engine is out) so now I have an auto GT-S, its still extremelly fast, especially with mods. Basically the manual allows you to rev higher when doing an ET race, which means quicker out-of-the-gate acceleration, so performance wise its better yes, its got faster acceleration, a manual will get to the top speed quicker, as you can shift it yourself instead of letting an auto cpu decide when to shift. Thats the difference, it still has the same engine, and the same displacement, I wouldnt mind having both myself, one for racing and one for commuting. Sometimes I wish I had the extra bit of juice but honestly your not losing THAT much hp, and in day to day driving who cares? Your not supposed to be speeding anyway.
You dont want to start getting tickets at 16, because your quickly going to deteriorate your license points and thats bad. Besides, once you get a body kit, all it takes it a 50mph run in with a pot hole, youll quickly decide speeding is bad.
It comes down to this, if you plan on racing and doing a considerable amount of performance work to the car for racing purposes and spending alot of money there, than get a manual.
Also, your an inexperienced driver, not your fault its just something you have to practice, you cant just wake up get in a car and drive great. This car is small and nimble and very quick for its size, it also isnt very tough. You dont want to wreck this car trust me, Celicas are like soda cans, then dont do well fighting SUVs, or any bigger luxury cars. They can take a hit, but it just about anhilates everything but the frame. (Ive had my share of incidents, none my fault) Even a truck backing into me out of a driveway utterly obliterated side of my car...So in your case Id suggest either learn how to shift a 6 speed flawlessly, or get the auto.
The automatic wont hinder you any, and is great if your an inner city dweller, trust someone who drives in the city alot, it gets old up and down shifitng every 50 feet at every red light. The auto will also keep you more focussed on your driving, instead of what to do next. Plus, its plenty fast for you (you shouldnt street race anyway, you dont have enough skill and its illegal), so unless your a good shifter whos had lots of practive power shifting and double clutching and what not, youll just be slower on a manual when your at the race track, and then your tiny bit of extra speed is redundant! True race shifing takes lots practice, and even if you perfect it youll only be running 15s and high 14s (with mods).
I myself had a minivan for my first four years of driving, and am thankful, because I learned how to drive very well before getting a really fast, expensive and fairly fragile sports car.
So you can go about this a few ways, learn to drive a stick on a differnt sports car, get an automatic Celica, or get a cheaper car to drive a few years, then when your 18 or so get your celica and youll already be a pretty good driver. Obviously there is the lure of having it now, so I totally understand that part. Im just making you aware of the different peramiters. You could always just get a cheap truck or something and start saving all your money to pour into the Celica when you get it later? You could then get it and do instantanious modifications to it with all the money you saved up.
I hope you dont feel like I was lecturing
, I hope at least you consider mine and the others experiences and take heart.
Good Luck whatever you decide