Took a while for someone to show up with an answer for ya, but here goes.
I believe the SPS has the standard 700 trigger and they are fully adjustable. Not something for the inexperienced, though.
A good Gunsmith can remove the factory "glue" adjust screws for engagement and weight and re-glue, but not below 4 lb. But, a clean, crisp 4 lb trigger will seem much better than what it is now. (we get 46 for this)
To get below 4 lb requires an aftermarket replacement trigger assy. Timney, Rifle Basix, and I believe Shilen still offer replacement assy's. These are offered in models that go as low as 4 ounces. Whew, (for benchrest only)!
Adjustment of the backlash and weight is fairly simple, but I wouldn't mess around with sear engagement. And the glue is there for a reason, if you touch the trigger adjustments it voids your warranty. On ANY part of the rifle. Just fyi.
I've probably worked on 100+ rifles during my time apprenticing in a local gun shop and triggers are always the first thing to be modified, the problem is, everyone has a different standard as to what they think is "right". It's purely subjective to the shooter.
Benchrest guys want about 3 to 4 OUNCES of pressure - that takes skill and precision that I do not have - and always is recommended to go with an aftermarket trigger in our shop.
SWAT and Tac teams want about 2 pounds on their triggers, which can be done on a factory trigger, but why? You can drop in a custom, three lever trigger from Timney or Jewell?
With the Remington 700 - you literally have the single largest platform for custom parts of any rifle out there. Anything you could want to customize, someone has already developed right for your action, and there are probably 10 people in line behind him to "modify" his design. It's the single largest selling, most predominant action out there for boltguns. So, if you can afford it, why not let the experts hook you up?
Here is a link to a drop in for Remington 700 models from Timney that I like, plus you can spec the pull weight when ordering, relieving some of the "tension" of doing it yourself.