Invidia Testpipes

The 03-05 Evolution 8 can see significant performance gains by removing the restrictive OEM catalytic converter. Replacing the OEM cat with a freer flowing high performance cat or deleting the cat altogether and using a racepipe (also called a test pipe or cat delete pipe) will allow your Evo's turbo to spool up faster and move more air, increasing horsepower. Most any catpipe or racepipe will bolt in place just as easily with a stock downpipe and exhaust as it will with a full turbo back system.

Notes:
Racepipes are for off road use only.
Check you local laws regarding emissions regulations before deleting your OEM cat