erinyes

hi all, just ordered a de-cat downpipe cos mine is blowing a tad, curious if this is gonna cause a spike in boost?its a STD '93 WRX. also, been reading about knocking bottom ends etc on similar cars, WTF?!?!?!help, how can i tell if im in for a big repair bill?im worried cos the car somtimes feel quick at all, and somtimes feels fast as ****, hoping its somthing to do with this tiny blow,but also thinking actuator sticking?or the boost solinoid, wher is this and how do i clean it out? REALLY appreciate any help here cos im worried that the new wheels and coilovers i have just ordered are all in vain thanks in advance