I like to use 1.5 x .120 or .125 dom in my cars 240s/rx-7s.
Reason being is that it smaller, takes up less room, and is easier to get the tubing out of the drivers way (head), which if your tall 6ft+ really makes a difference with head room.
1 3/4" is cool, but I think it just looks too big in our cars, and looks like it belongs on a off road truck, or rock crawlers.
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