What do you mean by "aftermarket bits and pieces"? As in exhaust and intake? And depending on what you mean with a lower budget, there's not much you can do. But then again, your low budget and my low budget are two different things. But if you have those, either go trans to get better gear ratio, or just do engine bolt ons/headwork: intake manifold, throttle body, better tune, VTEC conversion, cams, yadda yadda. But the best bang for your buck with your integra would prob be VTEC conversion or boost if you want more power with money spent