[lux hauler]

abcdefg,
Sounds to me like you need some tuning. As dead sled said, the 425 is not that bad an engine....if it's tuned right.
Remember....these engines are designed to make their power at lower rpm's. If your looking for an engine that'll pull to 5500 or 6000 rpm's with factory parts, you don't need a big block caddy. Stock....4000-4400 and these things are done. That's the way they were designed.....low rpm torque.