So the wife's new O2 sensor is sitting on the kitchen table, glaring at me. Maybe this will fix the p0420, maybe it won't. This task could be easy, it could be a huge PITA. The future is a mystery....

@pseudosavant - forums.nasioc.com is what you'll want to check out. I'm guessing that as it is a North American forum, the relevant noise regs will also be useful (I'm in the UK so have different requirements)

@SamWhited ... did you notice I was able to use the word "cavitation" in an answer the other day? mechanics.stackexchange.com/questions/9116/… ... thought you might like that ;-)

@RoryAlsop Funnily enough - it was the NASIOC crazy talk about gear oil that drove me here. Too much hate and bile.

Years ago, my older son (who was about seven at the time) and I determined that the optimal muffler for a WRX was: none.

I was replacing my stock muffler with a Prodrive round-tip and I asked him if I should start it up without a muffler at all. Wooo, that was pretty neat. We also decided that Mommy would be suuuper mad if Dad got arrested for driving a race car around the neighborhood.

@BobCross hahahah - I once accidentally ripped out the outflow pipes completely (drove over a large rock) - sounded like a TVR, but power was well down

the exhaust I have on my STi is mostly 5" diameter, but has one cat in order to pass regs, so is not a straight through

My exhaust is a refined 2.5 inch (stock) until the axle-back - the prodrive - it's just fine.

I don't touch WOT often but it's funny how it quiets down as the turbo gets more involved (not surprising, once you start thinking about the system).

I've only lost the one cat in a "removing the up-pipe with a pre-cat" "accident"

@BobCross yeah - I think once you at least get a clean flow path, and tuning between the 4 cylinder phases, you are best off focusing on other power gains. I do rather like hitting 7000rpm, but like you say, at that point everything gets very different

"What pre-cat? That up-pipe was always there!"

@BobCross heh

@RoryAlsop Let the record show that, as a US resident, I know what a TVR is. We are watching the "make your own electric car" episode of Top Gear while we eat dinner. :-)

@BobCross excellent - although obviously the item that really worked to put TVR on the map was the film Swordfish...

@SamWhited essential viewing (Top Gear generally, but Swordfish as well, if you are an infosec person, along with Hackers, Sneakers and Wargames)

@SamWhited I don't think we've seen you on Security Stack Exchange...

@SamWhited they are de rigeur at DefCon

@SamWhited Think my last one was in 2005 or 6. I keep sending my juniors though - they get a lot out of it

@SamWhited fair enough - we have a good bunch of folks hang out in the security chat though - where security is only occasionally on topic

Current list of room topics is: double-entendre, food, libations, nono-yolo, rory and then security

@Cyber-Rory Ah Wargames - that seemed incredibly cool when it came out. In 83, there was a trick on the vax where you could actually /bin/mail a line directly to /etc/passwd

Just remember to take that line out when you're done :-)

@SamWhited Nice work :-)