The two pipes perform exactly the same. The header diameter, as well as all other dimensions of the pipe are identical. Perhaps Harold is mistaking the Tecno Estoril's header (which is only 23 mm OD) for the Tecnigas header which is 28.5 mm OD) The raw finish pipes tend to hold up better because the welding is better.(provided that your exhaust mount bracket is in good shape then the weld quality is negligible) . The chrome pipes have welds that sit very proud of the base material and do not have as much penetration. I am pretty certain this is done for aesthetic reasons however the fact is that the prettier weld is not necessarily the stronger weld. The chrome pipes are also a bit heavier due to the rear baffle design, On these pipes since they are mounted to Tomos mopeds that already have weak exhaust mounts, that extra weight is not too welcome. And FYI I have been heavily involved in the moped industry for over 20 years, and have had my own business and shop since prior to the Moped Army's birth. As far as overhead is concerned, I Lease a total of 6700 square feet in what amounts to be one of the highest cost of living areas in the US. Case in point, I just wrote out a check to PSEG for 1 months electric that is probably on par with what the rent for the shop in Kalamazoo would be. As far as shipping, 1977 will realize that shipping parts from the coast as opposed to their central location in MI is going to cost more and take more time.
The choice is entirely up to you. If you want the bling of the chrome pipe and annodized muffler then that is the one to get. If you are looking for the better performer then get either, since they are the same. If you are looking for the cheapest route, or to support the dealer with more overhead, or who has been into mopeds for longer then get the raw finish pipe.