how low can i go

[lostmya]

I posted this topic yesterday but didn't get many replies. I was wondering if someone could tell me what the maximum you can get away with when lowering the rear of a 70 model c-10 with a trac bar suspension? A tech guy at cpp told me 3 inches but I have a few friends that say you can go 4 or maybe even 5 inches and still have ok drivability. If someone out there has experience with this please post, I plan on ordering a coil and shock kit from cpp as soon as I have an answer.