Well, I dropped off the Downey headers yesterday evening to have the 3 bolt flanges welded on and they called back at 8:30 this morning to tell me they were done.

The new 3.0 goes in next week. So, the exhaust will get designed and installed before the end of next week.

I still want to go with the configuration like the photo below.

How important is O2 sensor placement. Can it move towards the rear 3 or 4 inches without any problems? I think I can leave the cat where it is.

From what I've read 2 1/4" tubing from the headers back is probably good. Any reason to reconsider 2 1/2"? The new engine is a Jasper 3VZE.

I'm going to use the Downey header gaskets unless I'm persuaded otherwise. I've been assured that if I'm diligent in torquing and re-torquing the headers I won't have a problem. The guy at the muffler shop added that I should make sure to torque from the inside moving out towards each end.

Anything else I should be thinking about as far as this exhaust project goes?

 

that looks like the NWOR Y pipe setup as downey routs it under the tranny.

i cut the flanges on my Downey headers and used the gaskets they sent as well as the org manafold studs (not the hardware that downey sent). I have had no problems with the NWOR headers staying sealed with stock type gasket and stock studs.

time will tell on the 4runner as the downey install is only a month old or so.

 

I'm not using the Downey crossover. I'm having the exhaust guy do a custom job similar to the picture at this point. Obviously I can get creative since I'm going custom. I haven't seen a better configuration than the one in the picture. The exhaust will be protected well and should flow pretty good too.

I got the Downey studs. The exhaust guy gave them the nod over the bolts too.

As long as the O2 sensor is in front of the cat I should be ok right?

 

That's all that matters is that it is in front of the cat and behind where the crossover joins into the other exhaust. On my 94 it had a prewired rear sensor plug that just hung there so I cut it and spliced it into the front sensor wiring to have enough length to reach to the new mounting point!! I've also used the factory studs and nuts and have never had a problem after about a year of driving.