My 4Runner is in desperate need of a new exhaust, the muffler has 7-8 holes in it and sounds like a P.O.S. and in my searching here I've found a lot of people have been happy with a MagnaFlow with the 3.slow. I want to route the tail pipe out the back with a 45* downturn right at or just before the rear bumper and beside the trailer hitch, my only concern with this is exhaust coming into the cab through the rear window.

I drive a lot (90% of the time ~200+ miles a week) with the driver's window all the way down and the rear window down 3-4 inches, and even with the rusting out, side exit, presumably stock exhaust I can smell some exhaust during the first 10 minutes of driving then the smell goes away.

I've read that some people have had luck with the rear spoiler pushing fresh air from above the 4runner down behind it and thus keeping the exhaust out, while others say it does nothing. Since I do not have a spoiler would it be worth while to go get one from a junkyard and install it?

 

That is one of the main reasons why they put the spoiler on there. A wind tunnel gets created in the back of your runner while driving. And there isnt any way of it excaping other than the spoiler forcing the air down. My bros 98 runner didnt have the spoiler, when he had his exhaust put on, he just put a 90 on the back of the muffler pointing to the ground. Unless your plan on putting a tip or something on it you may want to give that a shot.

 

I have the spoiler on mine and can still smell the exhaust with the rear window down.