I'd find out what the pinging is. Are you new to 2 strokes? I had owned 2 strokes forever but didn't know anything about them until I started reading here (I thought I knew enough). Blaster's seem to be both prone and unusually venerable to air leaks. For piece of mind, I'd do a leak down test. Like stated above, slickerthanyou sells them for a fair price. If you're all stock (IMO) it would be a good idea to make sure you're running stock jetting. I think it's 230 main, 32.5 pilot and needle in the middle position and the air screw is like 1.5 turns out (going off memory, if I'm wrong someone will correct me). I would drain the fuel and oil and refill with known good quality of each (I always run 100% gas, no ethanol).
As far a mods. A good pipe, Uni filter and air box lid removed makes a noticeable improvement (must rejet afterwards). That's all I've done to mine and it put me up to a 280 main. I'm still running TORS, so I don't know about removing it. Judging from others reports the head mod is a good improvement for the money at around $60. Lightening the flywheel makes them more peppy, again around $60. I've not done the +4 timing adjustment but it's free to do yourself and reversible, so it couldn't hurt to try. Better reeds may help somewhere in there. After that porting is the next value in performance improvements (about $150) then let more air in with a bigger carb. Many mods are trade offs, improve this but give up that. I personally when to the suspension after pipe, filter and removing the air box lid. I did the 400ex rear and Banshee front shocks. I'll do port work, head mod and lighten the flywheel when it needs rebuilt. Until then wider A arms, front disk, longer travel front shocks and extended swing arm are highest on my list.