What not just take OEM headers & modify them versus paying $200 a pop for Brock's?(thebbbusa @ Sep. 05 2007,09:02) To make it easier you should make the first section right out of the engine (first 6" or so) in one piece that slips on to the rest. That's how a lot of mfrs are making them now. Makes it a lot easier to get on on off.
In other words each pipe coming out the engine would bolt to the bike, then bend down. The rest of the header would then slip on there.
If you really wanted to get creative, you make the parts I am talking about then go buy this from Brock:
Then all you have to do is make a crossover tube and mids to connect your cans like I did. Now I can use any slipon I want.
The biggest problem you will have once you settle on your design will be finding someone to mandrel bend the tubing, or if you can do it yourself, finding the equipment that can bend the uber thinwall tubing. My mids are actually a little heavy since the shop I used couldn't bend the super thin tubing.
What is the OD on your 2 bros headers? Curious to compare them to Brock's. I will give them a call. Thanks for the info. Oh, what about your stainless tubing? Find it locally or what?(thebbbusa @ Sep. 05 2007,17:26) The brock primaries are larger than stock, so are all other aftermarket headers. They keep the first several inches small to keep the velocities of the spent gases up so it gets away from the head. There are compromises to all exhaust systems. Where one can be designed for power up top, another might be designed for more grunt down low.
As I said, mfrs use stepped headers to keep velocities high. My Two Brothers header looks almost stock, just bigger pipes. Unfortunately my pipes are not stepped as you have seen here. I would suspect there is a slight advantage to stepped headers, but the only way to know for sure would be to do dyno runs back to back with stepped vs. non stepped on the same bike. Even though they are stepped, they are still starting with a larger ID for more flow than the stock ones have.
I would expect that you will spend more on the die you need to complete your project, than would make the whole effort worth it...unless of course you really want to have something special. Mountainmotor fabbed his own up and I did too. I am not sure of my exact power gains, but I do notice a difference in performance. I did it more because I liked the dual can look than anything else. If you want true performance you will need a stepped setup like the HMFs and Brocks.
You could cut the stock headers off and weld on new larger pipes, that's a thought. Thing is, you'd likely have dissimilar metals cause your stockers are iron and aftermarket you're gonna likely use stainless. But that's a thought.
The next point of restriction comes from the factory mid pipes. Once you take one off and look inside you will see why. After this point in the exhaust system I would venture to say there will be very little difference in performance gains or losses between the different can mfrs since most use the same or close core diameter and almost all are straight through.
Here's a link to my Winter Mod project, it's where the pics are.
Why weld anything when you can build it slip fit all the way ? That is after upping the size of the secondary tubing of the stock header and welding thin guage steel to the stock collector Y's .(customfab @ Sep. 06 2007,02:12) Good call on the mixed metal. I can weld some mixed metal but certainly would prefer the same throughout.