This engine had its tranfer ports of the "Aggresive trail ported" cylinder matched to the engine case while the engine is assembled,and while it is still installed in the frame. This can be done! It also works VERY well! Why cheat yourself out of power that the cylinder can produce? It took longer to prepareand tape than to actually cut and blend. The cutting and blending took about 7 minutes. Some cases require alot of material to be removed. Some very little.