Re:no downpipe
 

ok... lets see if i'm smart enough to explain this...


When the impeler spins on the turbo it creates turbulance right? right...

So if you have no downpipe the air is super turbulent after the impeler, but if you have a downpipe on their (or a short pipe minimum of 9 inches) it helps suck the turbulent air out. to a point, and it helps the air flow out of the turbo faster.

Re:no downpipe
 

uhmmmm I don't think it can get out nay faster as it doesn't have to travel trhu anything..after the impeller it's just open air, it's already out. And I've experienced that without downpipe it spooled up faster and had better top end to.