It is true. I dont know if you remember what Shells_n_Cheese went through, proving his BMW M5 time was legit, by giving up his entire tune, specific rims and proving that the gear ratios change (on some cars) when you apply the BBS_LM_R's.
It had been rumored/known for a while, aftermarkets made some cars faster. We just didnt know what Rims, nor realized the ratios changed after the installation. Because no one could get his ratios he finally "revealed" what was happening.