I'm currentley running an equal length 4 into 1 header with one inch pipe down to a 3" collector. The pipes are about 28" long, if I recall. As far as what jets are in the carbs, I truly don't have an idea. I didn't set this vehicle up. All the work was performed by a shop in Sydney, BC.(British and European Motors) where the previous owner and I went to look at the car together. Is there a way to find out the jet sizes on these carbs without a ton of sacry dismantling? I've never had the courage to get into carbs in general, and these Webers in particular, although I do have a book for them. Right now, it is in truth a long way down on my to do list, as the engine was running "okay" when I took it out of the donor car. I've got a ton of work to do before I can even fire this thing up and start messing with it. I'll be glad to at least listen to what you've got to say about improving things, though.