I can only say,.....
Don't expect it to change the backfiring much if at all.
Do expect it to richen the low/midrange circuit
Don't remove the whole spacer till you tried 1/2 first.
And most of all, I'll caution you against trashing the heads on those little bitty screws. They are usually very tight, and you need to use lots of heavyweight pressure on a Flips driver that is in good condition. Some here say that you should have a "jist" screwdriver for those screws,.....that a Flips driver is not the correct driver for them.
Others here tell you to use the small impact driver (sold at HF) to remove them.
DangMan wrote on 09/14/10 at 10:21:21: