The MZ sectional diagram of the ETZ250 exhaust on page 63 of the Repair manual shows a cone at the end, not a flat plate. The TS250 manual shows the same.
the ETZs have porting more akin to a moto cross bike, giving the engine the potential to rev much higher than the 6000 RPM or so that the standard engine is limited to by the exhaust design.
Porting on the earlier T/S engines is a lot different which gives better low down torque so I am told.
I have only ever ridden ETZs so have no idea how different the two bikes are.
With mine it really starts delivering at around 3500 (just like the standard one does) and goes on right up untill the 6K red line.
The transfer port arrangement is different on the ETZs - the ES/TS have 2 transfers (1 each side) & the ETZs have 4 (two each side) and wider transfer and exhaust port timing angles (7 degrees more transfer angle & 10 degrees more exhaust on the ETZ). The ETZ pistons are quite different, being about 5.25mm longer than the TS (most of the extra being above the gudgeon pin bore) with wider & differently shaped transfer port cutouts in the skirt.
I have owned both & the TS is torquier lower down the rev range - useable from 2.5K but best over 3K, with the ETZs requiring to be kept over 4k to make reasonable progress. Both the ETZ250 & 251 were (a lot) less economical than the TS250/1 as a result. As I no longer have the ETZs but still have the TS (for coming up on 28 years now) says which I prefer.
Barrow - as your bike can obviously take no more polishing, how about having a go on mine ? Looks like you have a Vape alternator/CDi fitted & raisers under the seat ? Any chance of a picture of the other side to show the TLS torque arm installation (you have reversed the fork lowers by the looks of it) - I have a couple of the Honda TLS brakes, but have yet to try one. Is the paint used two pack ? - impressive finish.
Placed an order on Ost2rad on Friday for some bits for my TS - off the road for a couple of years due to needing the gear change shaft O-ring changing (pig of a job) & it really needs a frame paint tart-up (15 years since it last got done & it shows !). Aiming to be back on the road next year when, I think, it becomes "historic".