LT1 roller rockers

I have asked alot of people regarding this mod. and I thought I might ask the experts. I have a set of gm high performance 1.6 roller rockers. I bought these for my 93 firebird formula. I was wondering if the engine has to be under pressure just to install the rockers. Also, I would like to know if I should go ahead and install a new set of valvesprings(any brand recommendations you may have would be appreciated) and if so what other parts I may need to make them fit. My heads and cam are stock. Thanks a bunch!  

Not sure what you meant by "under pressure".  Are we talking self-aligning rockers that simply bolt down and don't require setting lifter preload?

Going to 1.6s will increase your valve lift by about .030" and add about 2-3 more effective camshaft duration.  To make best use of this, new springs is what I always recommend, however many don't swap springs.  It's like cutting corners, which I never do when working on the valvetrain.

Most guys like the beehive springs or, as a lesser option, LT4 springs.  They should be a direct swap and shouldn't call for a change in pushrod length.

Of course, if you're moving to NON-SELF ALIGNING rockers, then you'll need aftermarket guide plates and hardened pushrods.  That's add a little over $100 to the project if you get them from some place like SummitRacing or JEGS.

Explain the under pressure part.

Jake