header ground clearance?

[69sms]

Looks like I have around 3 1/2" of clearance from the header collector. Seems like not very much. Does anyone have their measurement that I can reference?

Also, is there anything wrong with running 2 1/2" exhaust into mufflers and 3" out the back? The only reason I am doing this is because the convertible has restricted space for 3" to the mufflers.

Thanks!