[v8Toilet]

The stock y-pipe looks restrictive but is actually a good merge collector. A supercharged Tundra with a stock y-pipe put down 300 rwhp on the same dynamometer where I put down 220 on the same day.

I’ve also changed mine for the SS-autochrome clone of the JBA y-pipe and didn’t notice any difference except more noise. It was leak prone so I went back to stock.

I say you should not mess with it because I believe it’s an engineered part made to support low and mid range torque. The kind of low and mid range torque a heavy truck like yours needs to get it moving.

From all my experience of trying different exhaust systems and headers, doing dynamometer runs, testing at the track, the only exhaust parts worth improving for more power on a naturally aspired V8 Tundra are the muffler (not the exhaust pipe) and the manifolds. Don’t change out the whole exhaust with a cat back 2-1/2” system but just change the muffler and keep the stock 2-3/8” exhaust pipe if you want the best most improved low and mid range torque.