My brother-in-law has his exiting out the side on his 01 Tacoma. It doesn't look all that bad, but I wouldn't recommend it for a 4runner. First, it might cause some issues with fumes and the back window down and also noise. Second, someone might hit or rub against the exhaust tip when they are getting into the back seat. They can get hot and could cause some injury/discomfort if a passenger did hit it. Third, if you wheel at all you will probably crush the tip on a rock. Lastly, you wouldn't be able to get sliders or use the stock running boards anymore due to interference.