Boostjunky

Hi guys
bought a hybrid blow off and a k+n panel filter for my sti type uk 03 this week, fitted both and took the car for a long run. Result not good! pops and bangs out the exhaust and the exhaust note was unpleaseantly louder (3" cat back that sounded great before), car wouldn't cruise smoothly and it wouldn't drop back to idle smoothly when coming to a stop, would hesitate on the way down. I also used half a tank to cover 80miles of medium pace driving. First thoughts blow off vale screwing up the maf. So I took it off this morning and went for another run, the pops and bangs went and the fuel consuption was better but still not right, the rest stayed the same . Anyway I thought?, it was working perfectly before I fitted these two items, could it be the panel filter. I put the standard filter back in. On start up the exhaust note was back to normal, a nice purposful rumble. Went for a drive, car ran much more smoothly and would happily cruise at 35mph in fifth again, idle wasn't as bad but still not right. However after driving a further 40 miles the idle began to calm down and by the time I got home was pretty much back to normal. Also the fuel consumption was normal too. Just goes to show I guess subaru got it right in the first place, why mess. My only thought is the PPP, a friend of mine with a WRX 02plate has these very same items and his runs great which is why I bought them, my car just didn't like them, anyway if anyones after a K+N panel filter for a newage wrx or sti, mines in the for sale section.
cheers from ross