My car is manual and makes 470rwhp. Thats about 520-530hp at the crank. I spent MAYBE 4k-5k to get in that range. this is for cam, heads, Xpipe, programming...etc etc. Its all natural, no spray, no supercharger..etc. If you are not going to spend time at the track and you want a daily driver that can just lay waste to people at lights, freeways and in the street... I would not worry to much about your rear end. Mine has held up fine for 2yrs+ and its a daily. Your rear end will go south when you start going to the track and put drag tires on....then your in trouble. I know alot of people who make over 400rwhp on stock rear ends and nothing has gone wrong, primarily because they dont put slicks on and go out and track ***** their cars.

I can tell you that the internals can hold up to 500rwhp pretty easily. The danger zone is about 600rwhp or 650hp+ to the crank or more. Now some people are gonna say "well mine or my friends/uncle/cousin/dad's..whatever....cars engine blew up after 400rwhp or whatever" because in reality there is no real set number other than stock that the internals can hold. But in most LS1's 600 at the wheels seems to be the limit. I've seen supercharged cars making 550 at wheels for well over 2 years without anything happening to the insides or the rear end. Because they stay kinda away from the track. It comes down to how you treat the car.

Now as far as 12k for that engine....thats crazy...I've seen so many 402 to 427 cu. in. short blocks LS1, LS2 engines naturally aspirated make between 520-600rwhp its not even funny. I just saw a 404cid LS2 dyno 540. the cost of the engine .....$4300 brand new shipped! plus heads, cam, push rods, fast intake..all bolt ons, tuning.. he spent a total of around $7700 including the engine. He's gonna buy an N2O kit for an addition 100-150hp boost for like 1k so yeah hes gonna have a 700+hp car for less than 9k with a new engine! Lots of options just look into them all before you make a decision.