over-lining a rod, or how to turn a 6wt into an 8wt?

[redietz]

So your "6 weight" rod performs considerably "better" with an 8 weight line...

THAT PRETTY MUCH MAKES IT AN 8 WEIGHT ROD NOT A 6 WEIGHT

One way of looking at it. Another is that it makes a slower 6 weight.

You're right about all rods being able to cast different line weights. As the poster above mentioned, manufacturers make an educated guess about what line weight most people will like the rod at. You're also right that faster rods handle overlining better, but missed that slower rods handle underlining better.