Update: Install is done. Everything is on the ClassicZcar forum
I went with the custom LHD Kameari drag header (octopus header) mated with a Fujitsubo Legalis-R muffler. Hit a few snags on the way but everything is mounted. The car sounds AMAZING and power to boot. It has such a deep note at idle and a smooth note while in the power band. I am a stock L24 btw. I did lose a little on the bottom end but gained huge on top end.
So here is the information I have gathered on JDM headers/mufflers.
1. There are 2 main Greddy/Trust headers for the L24. Both are discontinued. One is for the L24 in the Skyline and one for the L24 Z. Most generic Japanese headers are made from this design. It WILL clear the LHD steering column. BTW Greddy USA has 2 S30's.
2. The Fujitsubo SUPER-EX header will NOT clear LHD rack. This has been confirmed by a member on the classic Z car forum and my local Z car guru. Furthermore, there is a picture floating around the internet that is "claimed" to be the Fujistubo header on the LHD car. It is NOT the SUPER-EX and Fujistubo has only made one header for the L-Series and they say it is not the one in the pictures.
3. Most JDM mufflers will fit, modification of the flanges may be required as well as modifying the hanging mounts. The Fujitsubo unit is very tight. very snug, little to no room after its bolted on.
4. Another header that will fit is the Spirit Garage header, great quality.
5. The Kameari header will not work with stock SU's without modification (which I had to do, until I can get my Mikuni's)
hope this helps people in the future.