Is a 280 adpater plate/exhaust plate the same as a 260 adapter plate/exhaust plate that came from the factory with a oval tuner? I know that the 280 had a oval tuner and the later 260 had a oval tuner, so did they both use the same exhaust plate?

I have a 2000 merc 280 powerhead with the old drag electronics that I will be mounting on a factory 260 15" mid that came with a oval tuner. Is there anything I should do to the tuner, like cutting it well everything is apart? Do you REALLY think there is much gain in dry stacking the mid, I have heard the latest info form the top engine guys is that they do not dry stack anymore?