Does removing a cat converter change anything in how an engine runs? I have a '92 V-6 auto with 250,000 miles. I live in a county that does not require smog checks unless you sell a vehicle or buy one. I plan on keeping my runner until it dies and do not ever need to smog it. I wasn't sure if there are suttle changes or major ones in the overall performance. Timing changes needed or what? I just know my old Hi-Lux ran much better without the cat. Thanks

 

Generally cats are restrictive, and performance gains can be had by hollowing them out. I know lots of people destroy or test tube them.

However, if you are looking for performance from your exhaust system I'd recommend headers and a high flow cat. Keeping the cat will help the earth. There are better, friendlier ways to get HP without harming the environment.