Member Credit: Matt York
I just had the y-pipe installed today (5/2/98), so I have not been able to completely test it out, but my overall impression is very positive.
The installation took 2.5 hours (cusom design/install) and involved the cutting and re-welding of several components of the exhaust system. The O2 sensor was moved, and some new piping was added.
My first impression has been that the engine reves MUCH more smoothly and quickly. It also seems to run smoother at higher RPMs. Noise has not increased very much, but I did notice a difference.
You can see that the stock y-pipe has two main sources of restriction. First, the runner from the rear exaust manifold heads towards the FRONT of the car before it enters the y-pipe at a 90 degree angle. Second, the stock y-pipe is made of two halves that are welded together, this does not allow a smooth coupling of the pipes.
Stock Y-pipe Removal:
A Sawzall and a cutting torch were used to remove the heat shields from the stock y-pipe. Then the stock y-pipe, the flex tube, the O2 sensor, and the mounting flange to the rear exhaust manifold were removed.
New Y-pipe Installation:
The rear exhaust manifold mounting flange was saved and welded onto the new y-pipe.
The O2 sensor was re-attached between the flex pipe and the catalytic converter. The O2 sensor was relocated because the flex pipe had to be moved 3″ towards the rear of the car to make room for the y-pipe.
In this picture you can see the new Y-pipe. It is made out of mandrel bent stainless steel.
Here you can see the entire system. It is made of larger diameter tubing than the stock system, and the front and rear pipes come together in a less restrictive coupling.
All of the weld joints were painted to prevent rust.