Charlievee
Senior Member
I know old thread, but I'm new to the runner. My experience is mostly Mustangs and Broncos, but any real gain from after market exhaust systems is from deleting the cats. So zero gain from cat backs with the exception of Less restricted mufflers. Real gains will come from long tube headers, ported and port matched heads, mid pipe( x or h) with " high flow cats" and of course increasing the diameter of all. A CAI will give you a bit extra if you do the whole exhaust system and a dyno tune to adjust A/F ratios.Like others have said AFE or K&N seem to be the top choices. I think it's worth mentioning that intake and exhaust typically go together to help your engine "breathe" better. that said I believe that the AFE comes with a MAF sensor included in the setup where the K&N does not, regarding exhaust I am partial to Borla as well. here's the thing the MAF is key to this mod because if you don't tell your ECU that the airflow has changed the fuel air mix will never be quite right, the engine will actually "fight" the modification. if you replace the MAF sensor which communicates air flow data to the ECU the performance benefits will increase dramatically. If you go with K&N then I think JET makes an aftermarket MAF sensor for the 5th generation 4Runner.
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