Hi all, new to the forum and to Subarus. Just purchased an 04 wagon complete with the ppp. 

I apologise if this question has been asked a million times before but when I search for wagon suspension upgrade it shows every post with every word in!

I'm looking at upgrading the rear arb, i believe the wagon is 17mm to the 20mm on the saloon. Is this just a straight swap over? Also is it best to use a genuine Subaru arb or will a pattern part be just as good? Or should I use an aftermarket one?

Whilst I'm under there are there any bushes that you would recommend changing? 

Thanks. 

theres plenty of bushes available on the back end, all worth an upgrade since theyre fit and forget https://powerflexstore.co.uk/subaru/impreza-turbo-inc-wrx-sti-gd-gg-2000-2007/