I am new to the turbo world i am use to v8s ect.......
I have a 87 TII and am wanting to go 3" exaust all the way back with no cats ect.......so my first thought was header then some one told me it is a Downpipe ???what is it and exacally how deos this work i thought the downpipe was just the pipe coming down from the motor compartment or off the the manifold but then with a header it would come down anyway i am sort of lost please explain.......?

 

The downpipe comes off the back of the turbo, and connects to the catalytic converter. Watch out if you do this, as you will get boost creep.

 

well the header will just route the exhaust out the back. bye bye turbo in this case....

downpipe takes into account you need to reroute exhaust to spool the turbo as well.

thats my understanding.

 

Manifold bolts to engine. Turbo bolts to manifold. Downpipe bolts to turbine housing of turbo. All exhaust goes through manifold into turbine housing of turbo, then out the downpipe. So this is why you need a downpipe for a turbo car.

My advice is if you run a 3'' exhaust all the way back, get a bigger fuel pump, and rewire it.

 

I was planning going to 3 " all the way for sure is it worth it maybe to go too 3.5" also when i get the new fuel pump how do u mean rewire it ???