Originally Posted by dkl

Same here - did not noticed fuel efficiency nor performance increases after the upgrade. Although, the X was running/purring perfectly before the upgrade. I did the seals and rattle kit. I mainly wanted to do the seal, but the rattle kit was one of those "while you're in there, what the heck" sort of job

The S54 on the other hand, made a huge difference in terms of making everything more smooth and quiet. But I haven't noticed any fuel efficiency nor performance increases either. I did the Beisan stuffs on the S54 mainly for preventing the hub tabs from breaking more than anything else - for that, I'm happy.

But, as they say - Your Miles May Vary