The GM Performance Harness in both the 480 and 525 are plug and play. No tuning was needed on either one.

Remember that HP is a measurement of torque over time.... so the LS7 would kick it in the nuts due to that alone (more torque). Add cam/headers to an LS7 and it will make 600hp+ with perfect driveability.

The LS3 525 beats the stock LS7 across the board. Better HP and Torque

My 69 with the LS3/525 pulls my Corvette ZO6

Change the cam in the LS7 and 620-650 hp and 550 torque are easy #s to achieve and still very street friendly.

My last 69 I used an LS7 with a Texas Speed cam and ran 505 rear wheel at only 6200. Car was a beast. However my LS3/525 is also killer setup.

I just bought another LS7 for my kids build. Of course will do a cam change and convert to wet sump. Funny part is that just yesterday we started talking about selling the LS7 and buying a LS3/525. The money saved would pay for a lot of other stuff.

id go 430hp and contact Brian Tooley and pick a cam from the Hot Rod mag issue. picked up over 80hp from the 480hp crate engine with just a cam swap. ended up with 575hp max but very tight piston to valve .003
http://www.superchevy.com/how-to/eng...ick-boomerang/

I went with the 430HP LS3. Got the car running and then did a cam swap.
HP exceeds the 295/35/18 tires very easy. However the cam swap that I used does make car buck some what at low speeds but it is not a big issue and still does fine in traffic. It is 227/237 , 613/622 with 114 Lobe centers. Dyno numbers are very subjective but my car was 517HP / 497 TQ at the wheels through a 9" with 3.55 rear and a TKO600 with no other mods other than long tube headers. I feel it was a very generous day. Either way these LS engines are sneaky fast and start every time. They don't put out the same thump as a SBC can or BB does but way less drama on top of decent fuel mileage

430 and a call to BT will get you 550 with good driveablity and you'll save a few bucks over the 525 if you do the swap yourself. Adding the cost of tuning may wipe out and savings.

Downside is you lose the warranty.

All great info guys! I love real world experience! I'm wanting to change to a LS soon and this helps a lot!

I would just buy the 525!

1 If I buy a new crate engine I would keep the WARRANTY !!

2 HP cost money ! I may be wrong but how to you gain 45 hp with just a cam swap alone in this engine ? If it started with the same platform as the 430 hp engine that is a gain of 95 hp .

3 When i was younger I was told a HP would cost $100 per HP . Today's money would more like $400 per HP.

The 430 is a smog motor. To meet epa standards the exhaust side gets choked down among other things

Swap cams and badabing you get big power and great drivability.

i went with the 480hp version. Should fire up within 2 weeks. Might be next week. I wanted a little extra kick now and then in the future i will upgrade it. Nice learning curve and then tweaking everything else