http://www.speed-element.com/servlet/the-63/sp2-exhaust-performance-muffler/Detail

Its supposed to be made around the specs of a Greddy Sp2 muffler which sounds very nice on the sentras, I just didnt wanna have to pay upwards of $300 for just a muffler... any input is appreciated.

I'd ask people with your car to get sound clips for you before a purchase. I'd be weary... especially with something you're going to hear day in and day out.

If you can find a clip like Nels suggested that would be best. But understand this about exhaust, most of the noise properties come more from the positioning of resonators. The resonators cancel out sound notes and make a better sounding exhausts. The muffler does play a part in how it sounds but not nearly as much as the resonators will.

Assuming you want a "nice" deep sounding exhaust I would spend less money on the muffler and more on some resonators. They should be easy to find. One good option might be to look around on the Evolution or sti websites and see if someone will sell you a stock resonator off their exhaust. Captain ran an open exhaust with one resonator off my evo (probaly 10-12 inches long) located near the rear axles and it sound decent with just that.

Look at the higher dollar exhaust to get some ideas of what to shoot for. A lot of HKS exhaust run two smaller resonators. you pay more for those type of exhaust because they have spents hours tweaking the placement of those to get a good sounding exhaust note.

Well hopefully soon I should be taking the car to an exhaust shop to have them weld in an 18" or bigger resonator in the catback. From what I've read on other forums for the SpecV is that the resonator alone will cut out most of the rasp that I experience at higher RPM's. The muffler is just an idea, really it's just something to have welded in place of this eBay N1 I have on there now, and maybe give me a different tone.
Spec's are notorious for being loud with just a header attached but mine is especially different seeing as I don't have either of the 2 cats it came with and this catback I installed did not come with any resonators so therefore it's a bit on the raspy and loud side