SIP 'performance' exhaust

I put a Stainless SIP performance exhaust on my PX200 engine and after only 300km I have a hole in my piston!
I looked at the spark plug a couple of times and it looked ok so my jetting is fine.
I’m guessing i have to change my timing if i don’t want to renew my piston every 300km, can anybody tell me at how many degrees my ignition should be set, and what jet I need to be on the safe side? I did a search on this forum and didn’t find a correct answer for my problem, but somebody here somewhere said that i would need a 122 main jet,is this correct?
Do I need to drive with 98 octane fuel with this exhaust or can i keep driving with 95 octane? A friend says that 98 makes the engine run cooler…

If you made an hole in your piston it is correct you suspect of a too mutch advanced timing.
In your standard engine your time should be set at 23, but check it with the strobo, sometimes I saw brand new PX with the timing set wrongly, but a standard engine has a large margin of tollerance.
If the strobo tell you you are at 23 go to 21.
But it is very probable the strobo will tell you are running even more advanced then 23, since I know few guys running with the Sip exhaust that didn’t change the timing and didn’t report such distruction, even though after you change the exhaust with an expansion it is correct practice to correct the ignition timing.

The size of the main jet you should verify by yourselve feeling how the engine goes at full open throttle. I would say a correct main should be 120. Just try which one of the two you feel it is better.

Check the spark grade you are using is of the correct grade.
In your standard engine should be 7 on KGK scale. You could use 8.

You can still use the 95 octane.
You didn’t made such a radical tuning that should change so many things. Just get the basic out correctly.

Good luck.