I have a new to me 2004 4runner 4.7L with the TRD cat-back exhaust system.

I like the throaty grumble it gives in town, but I do alot of Interstate driving during riding season (17K miles in 5 months on my '96 4runner) and the drone or exhaust note at 1700-2000 rpm gets really annoying after 8 hours or so on the road.

I am looking at what it would take to take the TRD system off and put a stock exhaust system back on. The current TRD system has a single pipe coming from the cat to the muffler, single pipe exiting the muffler and going to the passenger side rear wheel where it Ys to both sides.

My main concern is gas mileage. Will going back to the stock exhaust system increase or decrease mileage?

Is it as simple as replacing everything from the catalytic converter on back only? Or are there other considerations that need to be looked at?

Thanks for your help!!

 

My guess would be a decrease in gas mileage. If you look in the summit/jegs magazine they sell silencers you can just insert into your tail pipe to quite down the noise when you want to. There a cone like shape. I don't know if it will work for every application but its worth a look.