In preparation for my installation, I really did not like the “step down” in the Supersprint connecting pipes between the header collector and the stock cats. After making the cut in the OEM cat pipe, I was able to see the reason that Supersprint added this restriction. The restriction makes it easier to install the connector pipe into the cat pipe given some freedom of placement along the cat pipe. This issue is illustrated by the following pictures which depict the cat inner and “shield” bores and the step down bore of the connecting pipe.
Depicts the cat bore as cut
Depicts the cat bore as cut with the connecting pipe restriction as delivered
To facilitate better flow, I had my shop expand the cat inner bore until it touched the outer shield bore. This is illustrated by the following picture.
Depicts the cat during bore expansion
Depicts the cat bore post expansion
This allowed me to expand the connector pipe bore as depicted in the following picture.
Depicts expansion of the connector pipe restriction
The final step was installation of the connector pipe into the expanded cat bore and the application of a single weld fusing the three ends of the inner and outer cat bores and the connector pipe bore. Note that I did not use the collar pieces shipped with the connector pipes. I believe that this set up flows better.
A great deal has been said about the application of the springs on the collector pipes. I found a real easy way to get this done using a simple cotter pin removing tool (looks like a bent pick with a screw driver handle. Simply insert the pick end into the spring end which goes on the collector welded tabs and rotate the pick. The spring snaps neatly into place in the welded tubes – 5 seconds for each spring and you are done…