KrayzC has the EF Yak with BME 58. Lots of posts on it. He's run it mostly with the ES composite pipe and is currently running it with my wraparound pitts muffler since the header to the ES pipe broke recently. Yes, it fits with tons of room and flies extremely well. He is travelling for the next week or 2, so I'm not sure if he has internet access, but you might try to PM him if you have specific questions.
You can see photos of his plane in various BME 58l threads
http://www.flyinggiants.com/forums/f...-eye-baby.html
http://www.flyinggiants.com/forums/f...t-exhaust.html