Default Spring Spark on 4.4.3, Radio Question

Hello all. Us over at S4GRU.com have been noticing that since the release of 4.3.3 that lte signals have been degraded significantly. This is likely due to the new radio, .13, which also enables spark. My question is, does anyone here have the know how about radios/modems to be able to see what was changed in the N5 .13 radio that enables spark (B26, B40). If it is possible to see what changed in the radio to enable these bands, then, is it possible to enable spark in previous radios (.15, .23, etc?). Many thanks for taking the time to look at this.