Are the intermediate housings interchangable for the turbo and non turbo of the second generation?

 

Yes. The TII center irons and S5 n/a have similar castings, but the stock ports are a little larger on the TII. But since the casting is the same around the port, it doesnt matter which you choose if you are porting the engine. S4 n/a has egr passages in the port, and Id avoid those.

 

Also the N/A centre iron is NOT tapped for a centrebolt for the lower intake manifold.. The TII is tapped. Otherwise the lower intake manifold face on the iron is the same.



Just throwing it out there, depending on what your project is (I find that I need a tapped centreiron for my manifold, so I have to use a TII centreiron.. My rotor housings are not studded, so I need the extra clamp force)

 

It's easy enough to drill and tap that center iron to suit. It only took about 5 minutes with the engine in the car, using the manifold as a guide.

 

The tapped hole already, in conjunction with the lack of EGR mount and taller OEM port timing, and availability also played a factor in my chioce.

 

Glad to hear that tapped hole alone wasn't the stumbling block ;-)

 

Would there be any T2 advantages in swopping the S4 intermediate housing for the S5?

the S5 has a 10 deg. advanced port over the S4