ron717

The 4th gen 4runner v8 has 3 cat converters, plus a resonator in the rear by the tail pipe, can the center converter just before the muffler be removed? The O2 sensors are at the converters comming from the manifold, not the converter near the muffler.

The Tundra only has 2 converters each comming off the manifold, and produces 5 more horses.

Any thoughts?

Sac State

For 5 horses, I wouldn't touch anything in the exhaust/cat. Too much to go wrong with the emissions/computer. Drop in a K&N filter for 5 more ponies.

ron717

How many cats does the factory borla exhaust system have?

SLC Punk

I thought that the borla system was a cat-back. So all of the OEM cats would remain intact.

Sac State

Yes, my Borla is cat-back. Didn't touch anything in regards to cat, MAF, etc. so my exhaust to the cat(s) is the same as any Runner. The system did come with a K&N type re-usable filter. With today's high emission/computer control systems, I would be wary of tinkering with anything that could adverseley effect your emissions or computer. For whatever reason the Toy engineers decided to put three cats on the Runner and two on the Tundra, don't know why, but for 5 horses, IMHO, it is not worth it. And it is illegal to monkey with the cat.