Going to change the cat Up-pipe in my wrx for a de-cat one but ive noticed some have flexi joints some slip joints and some with no joints so is there any difference???

 

any standard classic up-pipe will do or a new age sti up-pipe avoid the ebay bling bling ones which are large bore and will effect spool if you are stuck sourceing a up-pipe contact harvey on here as he has various specs available.

 

Often worth considering a venturi up-pipe like Harvey's or Laterals. I had one made for my car. When the engine is turning slowly it helps the exhaust gas to hit the turbo faster and spool earlier.