Turbo Diesel Exhaust ?

[Unique X5]

Wondering if anyone has replaced the rear mufflers to high flow straight through mufflers? Especially if Dyno tested before and after. The factory mufflers are very quiet and being a backflow design look like they would be quite restrictive. At least the E70 model has the exhaust tip exit the rear and probably less restrictive.

I see here on this forum some have mounted fake tips to look like the V8's. I was thinking it may be possible to use a whole saw and cut a hole in the rear of the muffler and possibly Tig weld a tip or rivet one on like someone has done already but actually make it functional. It would depend on the design of the muffler on the inside and may require further drilling to improve flow. Leaving the original exhaust pipe. It could be a cheap way of improving the looks, performance, probably economy and sound.