You bet I still have my stock cats for when I need them later! pretty sure it's the RT cats that are messed up. Putting the factory ones back on would be a huge step backward, so I placed an order with Fast Intentions yesterday for their brand new resonated test-pipes (will be first guy in canada with them). Will let you guys know probably next week if I get them installed.

Going to see if that fixes the problem first before buying a new y-pipe when I've already spent money to "fix" the old one. Sigh, I should have checked how much new ones by other companies are now. Put it into perspective, i paid $750 cdn back in 2004 and now the same fujitsubo is only around $500 cdn and there's knockoffs for half that much.

to be honest, i actually saw torque increase overall with nismo cai, RT cats, fujitsubo y-pipe and fujitsubo exhaust. it was significant enough to for me to notice and by my friends with WRX/STI. much easier to do crazy peelouts/donuts and even chirp tires shifting from 2nd to 3rd sometimes. right now, i can't even spin tires in first gear from deadstop with VDC off! I'm sure if i had a stock exhaust, the bigger y-pipes might have hurt my torque but if i say go for it if you are getting an exhaust and specially HF cats or testpipes.

 

damnit, not the RT cats that caused the power loss (0 torque). I've replaced them with resonated test-pipes, same problem. When I took off the RT cats, I noticed 1 side still had the honeycomb ceramic stuff (was loose and moves when shaken) but the other side it was completely hollow! Checked my Y-pipe and nothing inside, will check the catback later...

One of the O2 sensors from the cats looked warped badly but I've never seen a CEL before, and I don't think it will restrict exhaust flow so it feels weak in the back. God, I hope it's something simple like the ceramic stuff from the RT cats plugging up the catback! I've even replaced the headers so still baffled why there is no pressure coming out the back of the exhaust... when I rev my engine, sounds like just engine and minimal exhaust sound
one of my friends suggested my sparkplugs from my 2004 could be messed up too...

 

If the catalitic material is missing completely from where it used to be, you can bet that it either exited out of the exhaust system, or is lodged in there somewhere (likely with the loss of power). remove it and be happy. And....DO NOT BREATHE that stuff when you take it out, it's VERY bad for you.

 

how bad? ^_^

 

turns out i had the metallic material inside the RT cats. shop found and cleared out batches of what looked like Reeses peanut butter cups, ridges of metal and some chunks that were melted plugging things up. Instantly my car's exhaust can really be heard now, deep and loud (testpipes and headers = freaking loud). Power is also much better.

However, it's all lodged in the muffler section and the shop could only remove some of it. They took off the muffler, shook it and ran coat hangers and other things that bent and flexible into the fujitsubo muffler input and the two tailpipes to scratch stuff out. Now I can hear a bit of the stuff rattling at about 2k rpm cuz it's looser there... Any ideas how I can get out the rest of it out without cutting it open??

 

How about try using a shop vac to suck out the junk material from the muffler? If that don't work, I think you'll probably be best off getting a new exhaust system.