I disagree. A stock Blaster will respond well to a port job, so why wouldn't one that has a better exhaust? For the DG pipe I would think that any of the builders would do him right. Personally for his age and budget I would recommend one of these packages from Wildcard Racing (or a similar package from Flotek or Kennedy):
2 stroke porting base prices
Cleanup: clean up casting flaws and match port measurements
Single: $75.00
Trail : (mild all around power increase, better throttle response, cooler operating temps.)
Single: $125.00
Aggressive trail/MX port: Broad low to mid power delivery, great for moderate to fast trails and mx riding. Single: $130.00
If I were on a budget, I would at the minimum get the basic work, as it will improve engine response and performance (and you should see some increase in horsepower) unless you can come up with the $150-160 (including shipping) for more aggressive work. Depending on what the builders experience is with the DG pipe it may be beneficial to go as far as the aggressive trail/mx port as it is only $5 more than the milder trail porting from Wildcard. You would have to call the other builders for pricing but I think that Flotek’s site states that porting starts around $140 for the more aggressive work and I do not know about a basic cleanup job. Kennedy’s site is still not fully operational but he is quick to respond to PM’s and emails. I would imagine that a DG with one of these port jobs would run better than a stock Blaster with any of the better pipes. Moreover, when you do get money for the better exhaust you will have an even more noticeable power gain. For your riding style, needs, and budget I would work on getting a little engine work first and if you can get a better pipe for cheap then add it latter. Contact the builders and see what they recommend but you will have to tell them what you currently have done to your Blaster, how you ride it, and what your plans are for it.