Dinosaw

<p>The exhaust port can be opened up to 70% of bore - that is around 2-3mm off each side of the port but blend the sides of the port so they are straight to the port outlet where it meets the exhaust. Make sure you bevel the port edges otherwise you can kiss the piston ring goodbye!</p>

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<p>Uppers - I use a dremmel with a variety of grinding burrs and bits - I am getting to needing a right angled drive but not got one to date.</p>

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<p>The 357Xp has some weird durations on the exhaust port - around 146* and a short blow down figure of around 13.5* - it thrives on transfer velocity hence the crank stuffers so don't bore those transfers out too much - rounding and smoothing is good here!</p>

<p>Good luck</p>

<p>Steve</p>