98 Boxster: Cat Delete Pipes Vs. Muffler Swap

[jb92563]

I have a 01 S and it had 4 cats.

The upstream cat on the header pipes is monitored with 2 O2 sensors.

The rear cat is not monitored.

I bought the Top Speed Muffler and with the rear cats still installed, it droned horribly and was unbearable in the lower rpm range.

Then I installed the Top Speed rear cat deletes pipe (a short section of pipe replacing the rear cat) and no more drone.

The sound they make now is pure sports car, louder than stock when hitting the gas and about the same as stock when idle/coasting/cruising.

It also has a very nice "gargle" sound when letting off the gas. Awesome for less than $500 and DIY easy.

If you only have the upstream cat by the headers then all you need it the Top Speed exhausts and you should be drone free and no change to your O2 monitoring either so no codes to worry about.

If you remove a O2 monitored cat from your system then you will have codes and worse the fuel mixture will not be optimum and likely run poorly.

Not sure how the racers get around the O2 monitor issue but you need at least an upstream O2 sensor for the engine to run right.
There are post cat O2 sensor devices that can fool the computer into thinking all is well and avoid the check engine light coming on.


Ray