Huge deal possibly
Agreed with sg1586, you may have a chassis that needs rocker pipe, steel floor welded in place and pipe members along the floor of the firewall in 25.4 chassis as of 2007 or 06 that was previously good to 7.50 ET and now may not pass 8.5 et in some cases depending on how far out of spec the chassis is. Some of the funny car cages that were ok in 06 and earlier for door cars running 7.5 ET to 4.50ET 1/8th were in many cases incomplete relative to today's spec, requiring kidney bars and helmet bars and in some cases complete fab of funny car cage because they were not required in 06 and earlier for 7.5 et chassis certs.
This is exactly why I just re-certed my Beretta this fall, knowing that I was going to sell it this winter. Chassis rule changes apply to cars when they need to re certify, so having a fresh sticker guarantee's the new owner three years of racing depending on the level of certification, some are only good for one and two years in the top classes.
Bruce