I have

Pacesetter LT Headers
True Duals w/ Custom X-Pipe
Lingenfelter CAI
Pro 5.0 Shifter
LT4 KM
4.10 Gears on a Rebuilt Rear
160 Thermostat
Madz28 Tune
BMR Subframe Conectors

Whats next without going heads, cam, or nitrous?

 

1.6 roller rockers
underdrive crank pulley

 

turbonator

sorry....couldn't resist

 

In terms of making power looks like Chris is right.

1. 1.6rr's
2. underdrive pulleys (I would do a search and read more posts about them and you can decide for yourself if you want them)
3. And maybe an Electric water pump, but that's usually something you put on when your stocker goes out, maybe like 5hp to be had there...

You could always do some more suspension mods like LCA's or an adjustable TA also...

 

I thought the 1.6 rr were very minor gains, and there is talk of having to replace stock springs with atleast lt4 ones for some insurance? Am I wrong?

 

Yes, but also its in preperation for future mods. (Ahem... cam... ahem)
Gains are fairly decent, even on a stock cam. 1.6 gives you more lift = more flow. Also less friction, so they take less power away from the motor.

 

Rear end (12 bolt or 9")
Drag Radials
Suspension
Throttle Body
Ignition upgrades
fuel upgrades
Better clutch
Better flywheel
Better drive shaft
Better brakes

 

I gained 14 RWHP with my 1.6 rockers and springs.