First, I never said mini tub. not sure where you got that from? 2nd, both the QA1 6 link and the streetlynx mount to the front spring perches, which would place the bars outside of the frame rails. You'd only gain the difference between the width of the spring and the bar diameter. Unless you moved the per mounts inboard. At least, that is from what my research shows.
This is also noted on RMS's own website:
"The lower links attach to the axle with u-bolts, in place of the leaf springs. The front of the lower links also have the same dimension as leaf springs, so the system will bolt in at the stock leaf spring location,
or, if the MP inboard spring relocation is used, the lower links will bolt in that location as well."
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