...taken from wrxinfo.com:
"The main purpose of the up pipe cat is to keep cold start emissions low until the main catalytic converters warm up. Using a catless uppipe is a violatation of section 203 of the Clean Air Act. Each state has statutes that cover this subject as well. There have been no known reported cases of catless uppipes causing state emissions test failures."
...so everybody who's running a catless up pipe is breaking the law!!! See you all in jail. Oh NoeZ!!! :eek: Hahahah
I'd be willing to bet that Subaru started using catless up pipes because they do still have two after-turbo cats, so that's probably sufficient to comply with U.S. emissions standards. They probably also realized that the up pipe cat material can break apart over time and cause turbo failure and other major damage, which could cost them lots of money in the long run if they had to keep making such repairs under warranty. That also reinforces the idea that it's good to wait a few years after new car models come out to buy them - wait for the companies to iron out the kinks in the design and whatnot. Read: nobody buy the 2011/12 STi. Wait until 2013/14 at least.
Here's evidence: look at the changes that were made to the 2008 WRX and the 2004 STi. Are they bad cars? No. Are the models that followed "better?" Arguably, yes.
Now that I've gotten extremely off topic, I'll stop.
07 WRX (Albins 5MT + Blouch 20G)
Jorge Carrillo Tuned (365 whp/340 wtq)