Running On Your Period What Are The Negatives To Running Your Car's Timing Advanced, And For Any Extended Period?

What are the negatives to running your car's timing advanced, and for any extended period? - running on your period

I have a Honda 94 'Civic EX, the engine was rebuilt in '04 and I just had a new trans and clutch put in it. It runs very slowly after you specifications. He went up to the time and works perfectly. What kind of negative that I should look for both short and long term? Thank you guys for your help.