Best EFI harness and ECU for LS transplant.
 

Hello all! I am in the process of dropping a 5.3 LS engine in my 71 Firebird.
I am in search of a good plug and play setup that works good but not overpriced. I have looked at Holley and FAST and not sure which one to go with, or maybe there is another unit I should look at. Any help would be appreciated!

Try searching PSI?. They seem to be affordable.

Factory Ecu with hp tuners has worked pretty good for a lot of people.

I recommend PSI, veryy happy with mine

We've had very good success with OEM ECU and harnesses from Speartech on a number of swaps.

Speaking of psi...
http://secure.ultracart.com/catalog/PSI/
Looks like Charley's jackass.

Awesome!! Thanks for the feedback!! Never heard of PSI but definitely gonna check them out and Speartech as well.

If the engine is stock or close to stock, a factory ECU is a great option. If you want to play abit or have mods, the HP Tuners/EFILive can do the job but not nearly as easy as Holley. If you factor in the cost of SW,aftermarket harness and a WBO2...your not far off from aftermarket territory.

I run the Holley in my RX-7 and the Chevelle project is getting one also.

The harness is simple to install. I'm no computer genius and the interface is very easy to follow/use/navigate. Upload a file for your combo and then let the self tuning do the work. You will need to clean up the idle/cold start but the rest the Holley does for the most part. I will never ever have to pay a tuner $300-600 each time to tune my car when changes are needed.
I have never been on a dyno or seen a tuner with my LS7 RX-7. It runs like a raped ape. 1.5hrs worth of tuning on it so far.

Comparison:
new LS1 stock harness $700, used computer $100, tuning $500
(then retunes are more $)

or a Holley system with easy to use interface/software
new harness/Holley computer, WB02 sensor $1500 shipped online

Sounds like Holley may be the way to go. Thanks for the input!!