Sorry about the delayed response concerning your question- I just talked to Dday and he said the suspenion mods are legal for THS. Are you planning on running your car @ the GS Nationals in May- If so please stay in contact with me ( Haulz A), slow91z, badv6 and gnmaster for any info concerning the class. I personally help Dday with sponsorship and administrative functions for the class. Again welcome aboard and we would love to see you in May.