Could soldering electronics in a guitar with the "mystery solder" that came with my soldering iron effect the output of the sound?(not knowing what type the soldier it is!)

My friend just replaced some pickups with this "mystery solder", and now he is experiencing less output then the stock ibanez pickups that came with the guitar.
The new pickups (obviously) are BLUSA L 500 XL (Bridge), Dimarzio PAF Pro (Neck).
The guitar is an Ibanez Rg 4EX1

EDIT:... My friend just informed me that he had to rout the cavity where you put the bridge pickup in 2-4 mm to fit the BLUSA.... doing this... actually put a hole in the guitar(due to edge 3 rout). Im guessing this could be the culprit, any input? Input is definitely welcome!

EDITx2: The hole is about the size of a quarter... actually there are 2 holes about the size of a quarter.
I Survived The "Silent Deftone Cocksucking Forum"!-August 15th, 2006
Last edited by dez_cole at Nov 18, 2007,
i'd make sure all of your connections are good...i've used the mystery solder before in guitars and haven't had too much troubles. getting the good stuff prolly wouldn't hurt tho
"There is no position in sport as noble as goaltending"
- Vladislav Tretiak
My advice is to not let ANY soldiers near your guitar, no matter what kind, but whatever...
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