is it the same thing as a catalytic converter

uhh..not really...it replaces the cat. Since it's not street legal, no production cars ever came with a "downpipe". It goes from the end of the exhaust mani or o2 housing all the way to the beginning ofa "cat-backexhaust system". It eliminates the catalytic converter, so much better flow. A downpipe on a turbo car will most definitely help the engine in every way from spool-up to max-boost. Hope this helps.

? please explain that productuon cars do not come with down pipes.my car had a down pipe and a cat when i bought it.not all down pipes remove the cat.you can get them made either way.

I'm sorry, i'm half-retarded. I was meaning "race-pipe". That whole response was because i thought i was talking about race-pipes. I even wrote down-pipe in my response too, so i dunno. I can read, but not all that well.....