Do these things actually work?

I have a 2m 5/8 wave that I use mobile, and am told that a 7/8 wave will
give more gain. Can anyone confirm?

I'm told also that I can just take the 5/8 wave out and stick the 7/8 wave
in and it will load up. I doubt this personally - can anyone tell me if it
needs more or less inductance?

Any ideas where to get loading coils from in the UK?


Thanks all!

Sam
M1FJB