Moped Army

I have a stock puch maxi and i want to buy a pipe to increase a few mph until i can save up enough money to tweak everything else out. So i was wondering what pipe would be best for me, i read the puch exhaust page and it says all around the Proma GP is the best. but i was wondering if anyone else have tried any other pipes and what the outcome is? thanks. p.s. should i go with the OKO carb and what MM would be the most functional?