Originally Posted by SlickTrackGod

You should be about the right height if you use a 900lb spring with a 12" free height (I would not go lower in rate for a V8 car or you will hit the fenders in travel) But leave in the isolator- you'll need that little extra height. Without it you will be aprox 24 1/2 to 25 1/2" range and will ground out badly.

Also you had better think about aftermarket strut mounts that raise the strut travel- or else your strut wlll ground out against that too

I had a 12" 825lb spring in a V6 without an isolator that sat fender lip of 24 3/4". But I was about 300lbs lighter on the nose of the car than you and had very lightweight suspension and brake assembly that would not thrust upward with as much force as a heavier stock setup. I had very little suspension travel (about 1" normal travel and a max of 1 1/2" recorded with travel indicators.- Your car might travel more like about 2-3" and be slamming the bumpstops or grounding out the strut mounts and damge your struts. It won't be pretty. Better use good isolators and you should be fine

Originally Posted by SlickTrackGod

900 front 175 rear is a good guess to start with. Sounds like a choice I would start with.

I did not have stock bumpstops, mater of fact I had nothing stock to cut to the chase.

You will have several issues with going that low. Aftermarket trans xbraces will rub, Tqarm diff bolts will damage the chassis sheetmetal, rear bumps need to be trimmed for suspension travel, front a-arms invert and cause camber loss in travel, alot of issues you will need to address going that low. You better learn chassis dynamics and have alot of money or you will just be worsening your ride quality and handling.

Alos- going to a thinker isolator kind of defeats the purpose of going to heavier springs. You are putting in softness that will squish easier than the spring- just to take up gap