dont think you get huge gains mate, maybe 4-5bhp a a few ibs of torque.
not sure what if any other mods you have done but on a 172 i would get a panel filter, have your inlets matched and followed by an exhaust.
prob more gains from above and then when funds allow have it chipped you will get more band for your buck chipping a 1*2 with breathing mods already done than just a std car.
consider rs tuning in leeds mate he has a good rep for chiiping 1*2 he can do one of his own maps or he i superchip approved also. you dont get the 10-14bhp that they advertise on superchip website though.