Stick with DEI, they're number 1 for a reason. Viper 5901 is a good choice, they're fairly bulletproof... but if you want 100% bulletproof, the 5901's predecessors, the 791xv or the 5900sst were even better with more durable remote (you often can find them cheaper).
And you can install a 5901 in any manual, its just a pita to operate the way they want you to (or the way its designed to) - Many manual cars have a neutral safety wire and if you can find this, then any of these said alarms will operate JUST like an automatic, or only RS while in neutral. VWs, Nissans, and Subaru's I've found NS wire's in so far.... there may be more