I want to do the ISR mod on my 94 4runner with a 3.0. I have read everything that I could find about it on this site and I still have a couple questions. Has anyone seen a significant increase in gas milage from this mod? And has anyone thought about using a 3" plastic air duct like one from autozone. I figured that I would be easier than going to get a piece of pipe bent. Please let me know if you have any comments. Thanks

 

you will get better sound out of a pipe than you will out of plastic.

 

I'm not familiar with the plastic air duct pipe. I assume it's the flexible type with the little ridges. When doing this mod you want the inside of the pipe to be as smooth as possible. The whole purpose of this mod is to reduce the air restriction caused by the OEM intake elbow. A mandrel bent 3" pipe is the only way to go.

You won't see a significant increase in mileage. However, I did notice a very slight increase in performance. I do like the new sound though. And you might as well modify your air box while you are at it. Drill a bunch of holes in it and get rid of that little scoop that pulls air from behind the headlight.

 

I would encourage the metal pipe. I don't know what kind of plastic you're talking about but you have to remember that it gets hot enough under the hood to cook food. Probably be best to have something in there that you don't have to worry about.

 

I took my mock up piece that I bent out of dryer duct and took it to a muffler shop. The guys had some spare 3" pipe laying around and bent it for me. Took them about 10 minutes and it was free.

 

Thanks for the responses. I am going this weekend to get a shop to bend me a pipe.

 

I have a custom intake I made myself, so I don't have to go through with any bent piping. Mine is just a staight pipe, and the OEM intake elbow.