This was found on D&D Web site.
Install D&D Y-Pipe
Notice that both the stock Y-Pipe and D&D Y-Pipe have a slight angle to them. Install with angle facing down. The D&D Y-Pipe is shorter than the stock Y-Pipe so there will be some angle to the pipe. First install pipe and springs on the Y-Pipe to the pipe, then hold donut on pipe outlet while lowering pipe into can and install springs.With the added air flow that the D&D Y-Pipe has over the stock Y-Pipe it was necessary to shorten the Y-Pipe to keep the same Rpm as the stock Y-Pipe.