I had a buddy, when I was riding a KE100, who had a CR80. This was the stage when we thought 80's were kid bikes, and the most envied guys were the ones who had the 125s already. The guy on his CR80 smoked all his friends on the 125s because he could handle his bike.
The best way to impress your friends will be to read up on riding techniques, practice, and become a better rider. Since you are already experienced, there will be some information out there on technique that will make you a better rider almost instantly when you try it. Then, when one of your friends starts bragging that he has the fastest bike because he put a pipe, air filter, big bore kit, etc. on his bike, you'll leave him in your roost on your stock bike and make him look like a jack ass.
If you still want to do some mods to your bike, try finding some free mods that you can do. You don't always need to throw money at the bike to make it faster. Removing baffles and spark arrestors (may not be legal) and opening up the airbox with the appropriate jetting can do quite a bit to pep up your bike.
ThumperTalk is a good forum for dirt bikes, dual sports, and supermotos if you want to learn more about your bike.
Also, many of the people who read these forums are older and expect more readable posts with better English. Think about who you are writing to; don't phrase posts as if you are talking to your friends or parents; re-read your posts and edit them as if you were writing to a teacher, mentor, etc..