The stock combo is a roach over 4400rpm. Valve springs will need to be replaced and set. The turbo is the only thing keeping it going at all. Once the turbo is switched the stock intercooler will choke it really bad. Intercooler before down pipe. Stock converter will et better than most other $600 converters on a small turbine like a t31 although it ,might be a little harder to drive it out of the hole. 275/60-15 drag radial for the most potential. For e85 you can probably drop half a second with intercooler,more turbo (something with a 60-1 and 61mm turbine or equivalent and the 9.5 race converter. You wont be getting there without a lot of manifold pressure either. Still on stock down pipe. A downpipe is worth a little and will introduce a potential problem with the swing valve and fitment. Intercooler, converter and turbo=huge gains if you can feed it and the tune is close.