You could fit the 05 SpecV's Brembo setup.
they go for about 1000 dollars.
Make sure to Upgrade both front And rear. Any one who makes unbalanced upgrades to the braking system is asking for an accident.
asside from that. An OEM sized 2 peice rotor setup with willwoods will cost 1500 and will likely work Much better than stock while Not screwing up your brake bias to where you couldnt adjust it with pads or a custom Proportioning system.
asside from that.. if your just looking for street performance. I would STRONGLY SUGGEST NOT FUCKING WITH THE 01 BRAKE SYSTEM..
it was designed for the 3000 Lbs Altima and Will Woop on most brake systems In its Class. simply upgrade the pads and lines and call it a day
Matt Davis
www.b15sentra.net