I have had a 21hp V-Twin B&S Intek since 2003.....the first thing I did on a recommendation of a small engine mechanic - was to get rid of the puny little fuel filter and replace it with a autoparts store big one - that has been on there since.....no problems ever - but was told it was a weak point. 87 - 91 octane has never seemed to make any difference....I use fuel stabilizer though....and need to check the valves soon....almost 400hours now.
I stock the Fram G1 fuel filter. 2 1/2 times the size of stock filter and cheaper too. That and a shut off valve went in on day one. JD 350 w/Kawasaki 18.5hp rated.