@Karmona @calum @madgyver Interesting thread, as I've never run an Athena 170cc kit I can only agree with all the above comments.
One thing I would like to add though is you might like to consider a Tecno expansion chamber, possibly as well as the RH and DEP pipes. These are relatively inexpensive and from what I can see are basically an Athena pipe (which your above link recommends with the Athena 170 kit) with a clearcoat finish instead of black or chrome plating. A few years ago I ran one with a DEP silencer on an otherwise stock 1993 3NC French import and it made the power come in about 1000rpm earlier than stock with a sharp cutoff at about 9000rpm. I did some measuring of that pipe and a DEP I also had at the time and according to the A. Graham Bell two-stroke tuning book, all other things being unchanged, the Tecno delivers peak HP revs about 600rpm earlier than the DEP (basically my riding experience on the 125) whereas the DEP allows more overrev. So if you want a 170cc midrange monster for wheelies etc. it might just be the ticket, and it would be interesting if you could establish the correct jetting etc for all three pipes once you've built the engine.
Only thing I don't like about the Tecno is the clearcoat which bubbles up around the header pipe and is very difficult to remove. Eventually I managed it using rags soaked in paint thinner just wrapped around the pipe and left for a while (do this outdoors!) before wire brushing but I had to do this a few times to remove it all. I wish they wouldn't do this as it actually looks quite "factory" with the bare metal/welding heat marks:
https://www.ebay.co.uk/itm/233679367459#:~:text=Item description from the seller,41%2C PH 49-50.&text=THIS IS A STANDARD PIPE,WILL NEED A COMPATIBLE SILENCER.&text=WE WILL COMBINE POSTAGE COSTS IF MORE THAN ONE ITEM IS BOUGHT.
