If you need a good laugh today, go to the last couple of pages on this thread and read where they're talking about packing their new GSX-R exhausts with steel wool. Can you believe it? Steel wool!
Did somebody eat a lot of paint chips when they were a kid?
How loud is this modification anyway? From looking at it I'd say there's just not enough volume in that tiny little GSX-R exhaust can for any real noise damping effect.
Do the GSX-Rs they're getting these exhausts from have a catalytic converter on them? If so it's a bit more understandable for the final portion of the GSX-R exhaust to be so small because the original, complete exhaust (with the catalytic converter included) would result in an acceptable noise level.
*EDIT* Okay, I did a little research on my own and came up with the following pictures of a 06'-07' Suzuki GSX-R600 exhaust.
This thing is huge! How could you possibly find room on the EX-250 for this exhaust system? Now, if all you're doing is cutting off this system's cute little final few inches and welding it onto the EX-250's header then you're not really running any sort of muffler at all, are you?
The original GSX-R exhaust system (with it's catalytic converter) is a great example of adhering to sound engineering principles, finding out what will work correctly and then building an asthetically pleasing solution where "form follows function"
The exact opposite of that is this so-called "GSX-R600 muffler conversion" where a tiny bit of the GSX-R's exhaust is welded onto another bike's header. This is definitely an example of "form over function" or "form doesn't follow function"
The short version is: Looks good vs. Looks good and works properly.