Well it's all about personal choice (and budget) I don't think it's essential but it does look better overall. I'm on 20's too but with 35 profiles tyres, and feel like it does need lowering so I suspect that you may want to do the same too!
Not that much though because I don't want to loose to much comfort when driving, and 20's are already much harder than the steel wheels. Oddboy (correct me if I'm wrong) lowered his 30mm and it look just wright, so when budget allow it I will be going with the Eibach option!
Cheers, for the reply. I think maybe a will lower it 30mm, but i will se when its done, as im putting a full camper conversion in with maybe an elevating roof. Its annoying as these wheels are sat here and i cant put them on as my van is in the spray shop. Costing me a fortune in spraying, as the bumpers and mirrors are being done aswell as a full respray. It will be worth it though me thinks....
Well including the bumpers (textured) and mirrors, with the full respray its close to 2k. I know its a lot but they are an insurance specialised company and there work is fantastic. They also have to spend a bit of time with the bumpers as they are using high build primer to get a smoother finish. It should look good, i have got two captains seats with swivels from a toyota lucida. SS lower grill, wind deflectors, clear side repeaters, xenon bulbs, 2 side windows (tinted), DVd touchscreen double din headunit, and my 20" alloys. That is just the start lol. Next week i will be insulating, sound proofing and carpeting.