I keep hearing people talk about LTR's and siamesed and semi-siamesed.....what is the difference??? I'm gonna be running a Procharged 355 by next winter(hopefully)...what runners would be my best choice...hell what runners would be my best choice now? thanks for clearing this stuff up guys!

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Large tube runners look like stock, but have a larger internal diameter. My stock runners were 1.590" inside diameter, while my TPIS large tube runners are 1.660" ID. 0.070" might not seem like a lot, but think of it as the difference between a cam with .410" lift, and a cam with .480" lift. These runners are split all the way, meaning once the air exits the plenum, it is separate all the way down the tube into the heads. Siamese or semi-siamese runners have a couple inches at the top where they are not split. This increases the plenum area, and decreases the effective length of the runners, making them give more horsepower at higher RPMs than stock.

See the post in the Aftermarket Product Forum about "Why AS&M Runners are better than SLP runners" for pictures of the differences.

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