Are there any differences in the Bartolini mk1 pickups and preamps between instrument manufacturers? Or is it a "one size fits all" line? I'm looking specifically at the mid/high range of Ibanez and the Lakland Skyline series basses. I currently own an Ibanez SR655 with mk1's. They're...ok. The preamp could be a bit better, though. i was just wondering if they had models other than the split Precision-style humbucker (a P in a soapbar shell), or if any manufacturers had custom spec'd versions.