Hello to all! A guy I work with has a 2001 GS400, and his rearmost catalytic converter (intended to lower emissions even more) was making noise so he took it to a muffler shop, where the guy told him it'll run better when that 3rd cat is removed. I'm wondering if the ES350 exhaust system is designed the same way so I can do the same thing to the 2011 ES350 I got about six months ago. If any of you can give me some feedback, I'll appreciate it greatly. Thanx in advance, jj

 

My advice is: "if its not broken, don't fix it" If your ES is running well without any issues just keep it like that.

 

Your buddies car would seem to run better because the old cat was damaged and/or partially plugged. There are various aftermarket cats that are less restrictive which would give a little better performance but is hardly noticeable. In today's engines the performance improvements are gained by remapping the engine parameters in the ECU. But then again an ES is not a performance car so it's not worth exploring.

 

Thanx for your prompt & WISE replies, guys! I will follow your recommendations. jj

 

My past experience with 3-cat setup (two in headers and 3rd as clean-up secondary): removing the secondary 3rd cat and resonator will gain you up ~10 HP and lots of dB. The true gains are in having free flowing headers and Y-pipe and those with proper ECM tuning will get you ~30 HP.

Camry forums have some of this info as well. Quick google search yielded this thread:
https://www.toyotanation.com/forum/1...exhaust-3.html