Poor stringbalanced Yamaha BBG5..HELP!

[Ingemar]

I've got a Yamaha BBG5 passive bass
(like the one below, but in amberburst colour)

The problem with the bass is that the E str. has more output and puch than the rest of the strings (especially B str.)
A rather common problem with this construction
- alder body/one peace maple neck, I guess

I've changed the bridge p-up to an Kent Armstrong soapbar P-up, wich I hoped should read the str. better but, it just helped a little bit

I've also tested a lot of different string brands and gauges but they didn't improve the str.balance that much.

I've thought about to drill the bridge/body and string.all but the Estr. "trough body".Do You think that will help stringbalance??

I will appreciate every tips/suggestions from You

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[Ingemar]

If I should experiment more with string gauges...should I choose a lighter or thicker gauge on the E str. to help stringbalance in this case?

 

[Ingemar]

The orginal neck pup is a standard Yamaha passive (as at the piic in the link)
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Is there any j-styled fivestr. pups with adjutable polpieces that will fit this bass?

 

[Ingemar]

The bridge pup that I replaced the orginal yamaha J styled with is one of these
Kent Armstron soapbars
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[Rhythmalism]

I'd be nice if there were an easy way to lower the magnets on the E-string only. Maybe pop it apart and see if it can be adjusted? Raise the B coil while you're in there?