Leather upholstry and Alarm systems increase the value of the car when they are OEM. i.e. a Accord EX with leather is worth more than an Accord EX w/o leather. If you were to take the EX w/o leather and have it upholstred, it would still be worth less than an OEM Accord EX wth original OEM leather.

And I don't think an el cheapo pepboys alarm would increase the price of a car, no matter what make! I would just keep that in mind. Only one mans opinion.