I wouldn't swap them out myself, I think the 4 lug will be strong enough. If you do swap out to 5 lug you also have to buy new wheels. The cost would be to high for me to consider, the car is what it is.
Of more concern to me is the 3.55 rear gear in combination with the typical T-5 first gear ratio of 3.27 (or something near that). That combo equals an extremely low first gear overall ratio, virtually worthless except for "frying tires". It's real good at that, I would guess 25 to 30 mph top speed in first. Maybe it comes with a chain, for "pulling stumps", you could start your own business.
With gearing that low you won't need a powerful motor, you will be able to impress your friends and leave twin black marks on the pavement at will. It's gonna be glorius!!