It's about time to change spark plugs, and while I am in there, I am thinking about installing a set of Bavarian Auto high performance coils in my 97 540i. So before I shell out the $600, I am looking to see if anyone here has had any experience with these, or similar products. In past cars, I have had noticible improvement with upgraded coils, but I have also had no improvement on other cars.

Also, are Bosch platinium 4 plugs the way to go? Or stay stock?

Thanks

I'm not sure about your first paragraph, but I do know one thing...

Bosch 4+ Platinum plugs are the way to go! I just popped (and by popped I mean it took for forever) 8 of these bad-boys in my 540i..

The gas mileage definitely shot up, but that might've also been because of the gas price increase! (Nah, it was both!!)

Just drop the extra buck for Bosch 4+ Platinum; trust me, you'll be glad you did.

Ok, thanks for the input on the plugs. I'll go with them. Do they come gapped for a particular application? I guess they must, how the hell would one gap a 4 blade plug...

I don't believe the aftermarket coils make a whole lot of diff or gains. I'd spend the $600 elsewhere and then do this if you have nothing else left to change.