With the rear arms, as the dynotech arms are the same length as the rpm worlds, by using them on the standard chassis your giving a lot more rear end width as well. Apparently on the RPM ultra chassis the rear end was narrower making the width the same when you used the longer arms, also in the conversion kit there was a template to cut down the width on the back of the tub. If that makes sense
With the car having these arms front and rear they say it is the same footprint as a B4 or near enough.