Underseat Exhaust

I only saw them on a few wr250's but not many. I'm looking to attempt it this month. I have access to different welders, bar benders etc. If you have made one for your bike can you guide me in the right direction on "how to"? i have a FMF and a DRC Edge2 Processor tail light.

Thanks

Did you ever make your custom exhaust? I'm gathering supplies to make one this winter, will be my first homemade exhaust. I'm planning to use all new tube from the header back to eliminate the ex-up at the same time. There isn't much help to be found on the internet...