Uprate any mechanical part, and you transfer strain to the next weakest part in the chain.
Eg. Uprate the engine, the driveshafts or clutch can let go, uprate the driveshafts or clutch, and the gearbox may likely follow suit.
Fit shortened springs without uprated shocks, and the standard shocks won't last as long, etc, etc.
I'm lucky in that a friend does all the work on my car for nothing, and as it was his opinion that the mounts were fine, he didn't change them when he fitted the coilovers.
In your case, you'll have to pay extra labour if you don't bother with the mounts now, and then find you have to replace them a couple of months down the line. If they're as cheap as Blue Mk2 says, I 'd have them done now and know that you won't have the hassle of having them done later.