I have a 2004 Volvo S80 that just hit the 210k mile marker. It's been having a couple small transmission issues that seem to slowly be getting more frequent. The biggest issue is an occasional delay and loud bang into drive, or more commonly just a delay and a shudder. Lately I've noticed some rough transitions when driving too, although they're not very noticeable. I've been considering getting the TransGo AW55-50 shift kit or the Sonnax zip kit. The TransGo kit is supposed to address delay/bang drive engagement. Are these a good idea for my car or would they harm my transmission life? I'd like to address the issues before they get worse, my engine is very strong and I want to keep it going for another 100k.