On MicroMegas detectors for ATLAS Muon Spectrometer upgrade, tests on the noise are performed together with measurements of tracking efficiency, exploiting the cosmic rays as incoming particles. The MicroMegas readout channels are floating copper strips with different lengths, from 284.0 mm to 1 990.0 mm, capacitively coupled with carbon strips at few hundreds volts. Due to the wide strip length range, the strip capacitance affects the noise with different magnitude, leading a larger spread in the baseline along a tracking plane, respect to a configuration with same size strips. It also impacts the thresholds that are proportional to the baseline rms, with a settable factor. Especially if the variation in thresholds is large among close strips on a tracking layer, it compromises the time measurements for the μTPC procedure. To uniform the thresholds on the plane, a single-channel level correction can be applied, by an implemented trimmer in the electronic boards (based on VMM ASIC). Therefore, studies on the baseline and threshold were performed as a function of the strip length. After them, studies on the tracking efficiency were carried on as a function of the thresholds.