Is250 / Is350 Exhaust Swap?

[Gaugster]

This is probably stupid but....

Does anyone know the differences between the IS250 and IS350 exhaust? I only see headers available for the IS250 which leads me to believe that there is some difference. But what about the diameter of the system from the cats back or the y-pipe?

In theory the larger motor would require a larger intake and exhaust system but maybe not. The intakes look the same.

I am curious because a lot of people upgrade the IS350 with an aftermarket exhaust system. Hence the original IS350 system is just laying around in there garage. Could the IS350 exhaust be used on an IS250? Is there any advantage or are they basically the same with only slight (non-performance) differences.