The reason for the large pipe immediately exiting the turbo is to allow the gasses to completely escape the turbine. The action of the rotating impeller and the shape of the housing cause the gases to 'roll' out of the turbo, If the pipe isn't large enough they have a tendency to roll back into the housing and slow the rotation speed, thereby reducing boost and increasing lag. Once the gas has passed about 15 to 18 inches the flow has straightened out. A larger pipe beyond this point wouldn't do much good. In fact the tapered pipe actually increases the exiting gasses velocity. That's not to say an even smaller pipe would boost power. BAE did their home work and I'd stick with what you have. Bruce Benson > I need some advice. I have a single BAE turbo. The exhaust pipe that exits the turbo unit is approx... 3.5 inches in diameter. This pipe is about 4 inches long and then is reduced to about 2.5 inches and is connected to the muffler and then a similar small diameter tail pipe. Is this a necessary design? I think that the exhaust is being choked off. If I were to eliminate the pipe reduction and get a bigger inlet and outlet muffler, would I get more power? Or would this not provide enough back pressure and I would lose any low end that I have? Thanks for your ideas? > > Rich > > > [Non-text portions of this message have been removed] > > > > Before posting messages or replies, see the posting policy rules at: > www.dmcnews.com/Admin/rules.html > > To address comments privately to the moderating team, please address: > moderator@xxxx > >