I just installed my wsp ypipe and love it! while i was down there i realized that i need a new resonater and cat. converter! i've been looking at cat backs for a while now and the two that stand out the most to me are the Greddy SP2 and teh warpspeed. The SP2 is upwards of 500 while teh warpseed is only 295. The wsp is 2.5 witha magnaflow ss muffler. which is the best to go with? or if there are any i'm not looking at and should be please let me now! thanx!!!