If you want cheap and fast then a DSM is not for you. A friend of mine would be best to talk to about DSMs, they are the biggest pos's youll ever find. He had a 92 Tsi (one of 3 DSMs i think) that got the motor rebult 35830853 times, and finally replaced with the "cyclone" the jdm version of the standard 4g63T, which later blew up.
i say 6 banger fbody
or um if you want turbo a dodge 2.2 car, a shelby daytona or something.