Good write up.
http://ls1tech.com/forums/automatic-transmission/699277-whats-needed-4l60e-4l80e-swap.html
As for supporting mods, if you're going with boost what kind? Supercharged then get a pair of long tube headers. If it's a turbo kit like the one from Trick Performance then leave the exhaust until you're ready. Most nessisary upgrade is your rear end. Change the stock carier to a Detroit Truetrac. Since you would already be replacing the carier a regear is recomended. 1st gear in a a 4L80e is steeper at 2.48 vs 3.06 in the 4l60e. From the look of your Sig something like a set of 4.10s or 4.30s would make it launch hard.
http://ls1tech.com/forums/automatic-transmission/699277-whats-needed-4l60e-4l80e-swap.html
As for supporting mods, if you're going with boost what kind? Supercharged then get a pair of long tube headers. If it's a turbo kit like the one from Trick Performance then leave the exhaust until you're ready. Most nessisary upgrade is your rear end. Change the stock carier to a Detroit Truetrac. Since you would already be replacing the carier a regear is recomended. 1st gear in a a 4L80e is steeper at 2.48 vs 3.06 in the 4l60e. From the look of your Sig something like a set of 4.10s or 4.30s would make it launch hard.
