My friend has a 2000 TA with an LS3 stroked to a 416 in it. We're running the car with the 2000 computer. Car has ported L92 heads, custom cam and is on approximately 11.3 compression. The VE table is good and the AFR is 12.98 right up untill 5800, at that point it goes to 19.0, backfires and dies. Its only on 18 degrees of timing. Our tuner couldn't find anything wrong when he tuned it. We've tried a crank relearn and that didn't help. Could there be something in the tune that should be done different for the large motor that maybe we all missed including our tuner? Oh, I believe the car has 42 lb injectors and it has been tuned speed density. Thanks in advance for any suggestions. I'll try to upload the tune tomorrow when I can get internet access with my laptop.