Hmmm interesting idea BUT that pipe is for a 49 CC engine....In order to maximize the performance of the tuned pipe it has to be designed specifically for a particular engine...Has a lot to do with intake / exhaust opening timing , RPM range etc..Still the pipe may be more beneficial than the stock muffler....Looks to need some minor bending and fab work to get it to fit to the Dax engine....If you do it, let me know if it works cause I have the Dax 70 also....FWIW my 70 also does about 27 MPH max on the std 44 T (lotsa Revs!)...If you want more top end a smaller rear sprocket would be the cure although this would lower acceleration and low end pulling power...
Andrew