I run Turbo - Action 8 inch converters in my 904 both redone by Ultimate. I had a problem years ago with the " big " converter bolts being to long and bottoming out thus leaving a minuscule space between the bolt and the flex plate causing a flex plate cracking problem at the time. We shortened the bolts a little and it fixed the problem. I also use Loc Tite when installing the converter bolts also use it on the flex plate to crank bolts.