If you want to continue to use the catalysts I think the main option for headers is the Librands system. (easily available on this side of the pond , I don't know about yours)
This is now a tubular system which exits through the hole in the chassis on each side (originally it was a crossover system , which was good for long primaries , but very complex, and heat under the sump is not a good idea in hot climates)
The manifold itself will certainly help with breathing, and power development, the sound is dependent upon the exhaust system from there backwards.
Firstly catalysts , you can delete these, but this then may fail emissions tests, so most of us keep them. You can source catalysts with a lower cell count (200 v 400+) these will help but are more prone to fouling with duff fuel.
Secondly silencers, the standard MMC product at this time was abysmal, and almost any alternative is better. You can get these made up locally, but here they are available from Librands , a straight through design.
Lastly rear and tail pipes, the resonators that MMC fitted do not really work , but they look good to some, so optional. I would go with a straight through system which is shaped to miss the rear wheels and exits at the rear with a simple flared tip.
Others opt for a side exhaust coming away from the silencer just in front of the rear wheel on each side . This will certainly give a much louder sound, especially on the overrun , but can get tiresome on long journeys.
Plenty of options , your choice may be limited by what is available , or can be made up locally.
Last edited by MOG 615; 30/10/20 09:33 AM. Reason: Poor proof reading
