I can fully understand why you�d be pi55ed off. Everything about them doesn�t inspire confidence.

TBH, aside of the poor workmanship, I cannot see how these are going to give you any performance gain at all? The weld inside the port end is narrowing the cross sectional area and it�s is far from smooth which will restrict flow, then you�ve got the fact it goes from there to 4mm wider pipe back to narrower pipe where it joins the silencer. Unless it�s all wider it ain�t going to make a lot of difference. In any case, a wider diameter header pipe (more flow) will only ever make a positive difference at absolute peak revs when pumping losses are at their greatest.

The OTR blurb on the web site doesn�t make sense either?

�Power headpipe made from stainless-steel with 4mm more section compared to the original. CNC-bent and well constructed headpipe (1) with widened section for better acceleration and top-speed (2). The better gas flow improves noticeably the power and torque (3) compared to the original headpipes. This improves the throttle response as well as the power and torque, especially at the lower rev range (4).
Also the thermal strain of the single cylinder engine is reduced significantly due to the better heat removal and higher gas flow leverl (5).
Fits original and all aftermarket silencers!
About 0.9 kg less than stock headpipe!�

(1) Clearly not!
(2) Unlikely (unless you�re bouncing off the rev limiter all the time!)
(3) Not necessarily as increased gas flow means less exhaust gas velocity (EGV). EGV is more important than peak flow in exhaust tuning. There is a fine balance between the two � get it wrong and you loose power where you need it most.
(4) Wider diameter pipework significantly reduces the torque available at the lower end of the rev range due to reduced EGV.
(5) Heat removal will be worse with lower EGV, because the exhaust gases hang around longer at the exhaust port at all but the highest rpm.

A properly designed and tested header system can make a difference. What I see in your photos doesn�t inspire any confidence that the OTR headers have either been designed or tested properly.

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