Just wanted to save someone else the headache if you decide to replace your cats and muffler. There seems to be only 2 options for stock replacement type mufflers(ie... affordable options), the Walker and the Bosal. I had good experience with the Walker on the wife's Nissan Sentra. Not the same with the 4runner. The male extension coming out of the rear Magnaflow cat would not fit in the female inlet of the muffler. It WILL fit in the Bosal with no modifications. Luckily I didn't hack up the cat too much and I'll be swapping in the Bosal tomorrow. The walker eventually leaked at the union between it and the cat and it's going to be gone. As far as I can tell it will fit the stock cat and the Magnaflow will fit the stock muffler but not the Walker. I'll add pics tomorrow when I swap them.