I installed the MLM Peugeot 103 techno EDM circuit pipe (from Treats) on my 103 with which has a 70cc Polini cast iron kit/SHA 15:15. The performance was exactly what I had hoped for, until it cracked in two places (lasted about 200 miles). It seems well made, fit perfectly on the engine, and never had any impacts. I assume failure was due to vibration.
Not sure which direction to go next. Get somebody to weld it, or find an alternative.