I've spent a lot of free time over the last few days without finding a definitive answer.

I'm looking to upgrade the stock exhaust manifold on a 2000 Si and looking for fitment confirmation of the following:

JDM 98+ ITR exhaust manifold with heat shield?

Mugen header for JDM ITR?

Mugen Header for B16A EK4?

Toda B16B Header?

Toda B18C Header?

I'm running the stock USDM cat converter / exhaust, which is where I'm not find answers. From what I've read the JDM cat converters are shorter in length so I'm wondering if any of the manifolds above will bolt up to a US length exhaust/converter. I'm trying to keep this as clean / OEM / high-quality as possible. Also curious about rear manifold-to-block bracket fitment as well as O2 bung fitment. Essentially I'd like to find something that will bolt in exactly like OEM without any modifications.

Any suggestions / recommendations also appreciated.

Thanks!

 

ek4 stuff....same exact firewall..besides opposite orientation