You don't need a tune for an exhaust, first of all. You will be fine. The tuner can add the larger diameter piping for the exhaust afterwards...but I doubt it will do very much in terms of programming.
I don't see you running more that 250whp with those injectors...are your goals around there somewhere?
Yes, you car will run like crap. If you stay out of boost and control yourself and it is super close, you'll make it. Don't take it as a guarantee, but it "should" go a few miles. I'd really urge you get it towed if it is NOT tuned and also doesnt have an exhaust on it.
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