Where are you located? Is it considered a 'severe
driving area' as per the manual? If so, the interval
for t-belt change is 100000kms. Otherwise its
160000kms. And yes, its interference, so best not
to play with fire....
I don't see what the Tachometer and the T-belt have
to do with each other... maybe the CKP sensor??
One of the Honda techies on the site may be able
to enlighten you on that one...