As most of you know I'm replacing my 3.0L V-6 with another. I've thought of a 3.4 swap, but no time. Anyways I'm looking to install headers when I put the new engine in. What headers are the best and what should I do for the rest of the exahust? I figure that it would be a good time to do all of this while the engine is out.

 

I think Downey and NWOR make them for our 3.0L However, I am not sure which have a better reputation for headers. Hopefully some other will chime in on this.

I would go with 2.25" exhaust tubing with a free-flowing muffler..something like a Magnaflow or Dynomax. Good luck with your swap-

 

Anyone else know which is better?

 

What research I did I felt that NWOR were better, but not smog legal. Downey was it if you needed to be legal. I decided against headers because as I understand it, 1: the noise from them in the engine compartment will be louder and heard more through the firewall. 2: Theres always a possibility of mating surface leakage moreso than with the trusted iron. 3: Tim from DOA gave me the impression that the stock system was as good as any premade header and that performance gains would be slight if any. He also told me that running a 2.5" system from the manifold connection by the #6 cylinder all the way back was the way to go on any 3.0L engine.

I opted to go with DOA port and polish and cam regrind. Running this with a stock exhaust system with a 2.25" catback was fine, but when I upgraded to a full 2.5" system, I could really feel the power then. The 2.5" system was mated to the stock pipe about 5" from where it bolted to the manifold. Muffler shop could not get 2.5" pipe any closer. Look at my pics in "90 4 runner" on my webshots page for my exhaust pics. Now instead of a 17 second 0 to 60 as someone posted. I have a 13.5 0-60. Still not up there with a 3.4L, but better than stock.

 

I have a 91 V6 4Runner with 5 speed. Downey headers and exhaust system was by far the best performance improvement.

 

I'm also running the Downey air filter and my throttle body was bored out by Downey. Both mods gave improvements that you can definately feel.