Mid Grade gas vs High Octane gas - better performance??

[robcalderwood1 at charter.net (Rob Calderwood)]

Don,

I talked to a manager of a Citgo in Janesville a few months back. He 
admitted the regular and mid-grade come out of the same tank in the 
ground! Only the premium has its own tank. He said the regular meets the 
mid grade octane rating.

Rob

Don Walter wrote:
> My son's 1.8L 16V swapped engine was running pretty good but he felt 
> that it
> was lacking power a bit in the mid to higher RPM's  Initially we 
> thought it
> might be either running too rich or too lean.  I haven't had a chance 
> to put
> a meter on it to find out.  Today he filled it with Mid grade (89 octane)
> gas and claims that it pulls strong all the way through the RPM 
> range.  Does
> that sound right?  Does that support that it may have been too rich to 
> begin
> with and the more volatile fuel is burning better?  I don't want this to
> turn in to a science project discussion either so let's keep it at the 
> 5th
> grade level.
>