Back Box for 2003 Astra SRI

[B.S.Universal]

I am wanting a new backbox for my 2003 SRi.

Can anyone recommend one. How much is an Irmscher box? If I got
another make fitted would this affect my warranty?

Also would I need to declare it to the insurance company?

Any help would be appreciated.

 

[R. Murphy]

I would guess it counts as a modification, which will affect both your
warranty and your insurance