Free flowing big bore 1+1/2" pipe throughout with baffled (slightly) baby cherry bomb silencer. Complete with U clamps, Loud but not annoying, easy to fit, easily clear dynamos and alternators). Made with heavy gauge steel now have "Newmans" ported outlets, (Dave Newman developed a ultimate port profile for reliant race heads in the 70s and kindly let us copy his design) and fit on all standard engines and as they are "pre ported" you can match profiles with a diegrinder on your head for even better performance. Also comes with small extra baffle if you need to get the noise down. The pipe mouths are oval with 25mm at high point and 23mm across, 1" outer die on primarys(23mm int). All primarys are 11" apart from no1 that is 12+1/2 (needs to clear the alternator) same layout as factory pipes with bigger bores. 1+1/2 inner on final pipe.