Need to replace shocks on stock C4S, can i use m030 shocks?

As the title says, I need to replace the rear shocks on my C4s which has the standard suspension. The prices he was getting for rear shocks were around 300 or so each, i saw on design 911 that they have a m030 replacement shocks (Front and rear) package for £700 so asked the garage to go down this route as the front shocks have some rust on them anyways. Just for my sanity, is this an ok move to make? Price wise it works out well but wondering if the m030 shocks with stock springs is ok? I realize there is a ride quality component to this, but really just want to know if this is an acceptable trade of parts?

As far as I'm aware the 996 C4S had M030 suspension fitted as standard so you won't see it as an option code on the build sticker etc.

I'd be surprised if M030 was standard on a C4S. I had one and a 40 year at the same time and the C4S felt nothing like it. Much more compliant and less crashy.

I definitely dont see it in the option list but the garage did call today and say its on standard suspension. Right now the rear shocks are completely gone so not doing anything, as the M030 shocks were the same cost for all 4, vs (close to) only 2 of the rear standard ones Im hoping that its at least an upgrade from what I'm sitting on. Any idea if it will be a problem? The garage doesnt seem to think so but wondering if anyone has experience here.

I don't think there is m030 C4S suspension. The 'm030' package you mention has 22-113344 bilstein b4 front shocks and 24-113359 rears, looking at a bilstein catalogue these are the only b4 shocks for a 996 4s (listed as 'm030'), and are also listed as 'm030' for a c4/turbo (the only b4s available for these models). The PET doesn't list an m030 for the 4s, the 4s has its own part numbers for shocks/springs. The D911 site seems pretty confused and lists the same part numbers as 'm030' and 'original'. I recently had some 996.1 c4 m030 front springs on my 4s and they were a smidge softer and smaller diameter (14mm vs 14.5mm) than the original 4s springs, similar ride height (poss a touch higher). The rears looked identical. Basically I'd have thought you'd be fine either way (doing just the rears or all). 2x 24-113359 rears are about £350 on D911. To throw another option out there I've koni special actives on the back of mine which work very well with the factory fronts.

If you like the ride now, or without M030 dampers, I would be very, very carful going this route. My car, an M030 C4 from the factory, I did a suspension refresh 18 months ago, and went for the Bilstein M030 you are talking about. I found the ride horrible. Also, the front dampers from Bilstein, B4 anyway, are definitely not as firm as oem m030 dampers. So you had the front being a bit softer and the back being far, far firmer. I managed about 1000 miles on them before ditching them and just putting on some oem dampers with standard springs too. Far better. The damper tends to firm things up far more than the springs when talking oem and Bilstein B4 range. I sold my complete strut assembly with Porsche springs and all new hardware like top mounts for about £300 I think it was. I just didn't like it. Go for standard dampers on the rear. They may cost more, but the Bilstein M030 are far too crashy. Bilstein say around 15% firmer than oem versions. The back end just skipped over every corner unless billiard table smooth, and ruined the car.

Simple: call Center Gravity and ask about their CGGT dampers designed specifically for 996. I've driven their C4S test car before & after - night & day difference, and there is no better set-up for UK roads IMO.