I've just started by 3.4L swap into a 90 4Runner, replacing the tired 3.0L. After much research, I plan to use the Doug Thorley headers on the 3.4, installing just the headers onto the engine, bolting up the trans, then taking the engine/trans combo down to my favorite muffler shop. They've done excellent custom work for me before. They will cut the flanges from the Thorley crossover to the passenger side, and will custom create a new crossover over to the driver's side. Then I'll have the new crossover ceramic coated like the rest of the system, install it all into the 2nd gen 4Runner, then the same shop will finish up the exhaust down the driver's side.

Do you have a manual or an auto, rebel?

R150F 5-speed manual trans.

That R150F..... that's the one that came in the V6 90-95 4Runner US manuals, right?

Yes, correct. I've now changed my plan slightly. Last night I pulled the 3.4 complete with the 5-spd trans and t-case still bolted on. I bought some 2.5" mandrel bent U-tubes and along with the Doug Thorley passenger side crossover, plan to cut, section my own driver's side crossover now that I can see, with the bell housing still attached, the shape it has to be. I also got a 6" SS flex joint to be part of the crossover. I should have plenty of firewall clearance with a 2" body lift and the t-case mount which raises the t-case about 2" and tilts the engine forward a bit away from the firewall.

i got the same questions but i was just thinkin if you got the motor out and if your gonna run the stock manifolds, match the ports on the exhaust to the manifolds using a dremel to make them smooth and the same size, also if you want jet coat the inside and outside of the manifolds which will lower your EGT's and gain you a lil bit of power but will keep it cooler, done this many of times never on a yota but wouldnt be no different. good luck

I will probably use the stock manifolds for now. I plan on swaping the tranny too (auto to manual), and since there will be even less space in the engine bay (clutches), I wont try to fit anything that might compromise the tranny swap in the future.

Old thread I know but has anyone had any luck with a header for the 3.4 swap for a 2nd gen 4x4 4runner?

Don't waste your money or time. Headers are not worth the money for an NA application. Honestly nothing is worth the money for an NA build, jsut do a tune up and enjoy it.

If you want more performance boost is the only option (well you could do nitrous but I am not a big fan of it by itself).

Preferably a turbo as the supercharger is WAY WAY too small for the engine.

Yup, I did end up going with a set of Doug Thorley headers for the 3.4 engine, changed the dump from the passenger side to the driver's side with a flex coupling. Used some 2.5" mandrel bent U-tubes, took my time and fabbed the new crossover using some of the original Thorley crossover tube and the new tube. Welded it up after a test fit and leak test, then had Jet Hot Coatings here in Tempe ceramic coat the inside and outside of the new crossover and the left header bank (had to slightly modify the output angle of the left header downpipe). It's been on the engine for over 3 years and about 12,000 miles with no problems whatsoever!

Obx headers here with a self fabbed crossover underneath.

Looks the same as thorley's but lots cheaper.