I have a stock 85 shelby charger. It has never been messed with. Bought it from the original owner{older guy} 2 years ago. I'm not interested in doing a t2 upgrade or adding an intercooler yet. I was thinking about doing a 2.5 inch exhuast from the turbo back with a high flow cat and splitting it to dual exhuast at the rear axle with 2 california turbo mufflers. [The swingvalve is still 2.25 but will accept the bigger pipe.] Also thinking of adding a stage 2 cal[14psi]. That's all i would like to do at this time. What kind of performance gains should I expect and any guess as to what it would run at the track[1/4mile]? Also, will removing the cat make a large difference? Thanks for your feedback in advance.