I have a 5.7 350TBI engine......I don't really know much about engines, but i know i want to get mine to around 400 horses,i want to know what combination of heads,cam, intake, etc could get me in the range i'm lookin for....Right now its stock,the only thing i've added to the car since i had it was headers and dual flowmaster exhaust...By the way the engine is in a 1990 chevy caprice and its a ex police car.....So any input i can get is greatly appreciated, thanks in advance  

If you don't know much about engines, what do you know about 400 horsepower that makes you want it?  

i know enough to know that i want alot more horsepower and torque than my stock engine is producing.....  

I guess that's a better answer...

Increasing the output of an engine with a speed-density system is almost always going to require a re-programming of the PROM. Since this case involves increasing the output very substantially it's certain that you are going to need a chip burned for this project.

The stock TBI unit could end up being a bit of a restriction depending on how wild you decide to go. The stock TBI piece is said to flow around 400-500 CFM depending on who you're asking, and no matter what exactly that figure is it isn't much airflow capacity. A 400 horsepower 350 should demand somewhere around 550-600 CFM depending on exactly what you think 400 horsepower is. You will need larger, aftermarket fuel injectors as well to support this kind of power.

Since your fuel injection system relies on a manifold pressure sensor for input to the computer the lobe separation angle of the camshaft needs to stay wide to reduce overlap and keep vacuum high. Duration will have to be increased significantly over stock if you're hoping to add 150+ horsepower, but the duration can be cut back slightly if you invest in an especially good set of cylinder heads....

Vortec heads are always a solid choice since they make good power for the cost but there are better cylinder heads available but this all depends on your budget. All I know is that those stock swirl-port heads are completely junk and need to go if you want "a lot more horsepower than stock."  

On the cmputer side, yeah, you'll definitely need to have a new e-prom chip burned for the car. That's easy, Hypertech and Superchips make them.

On using your TBI unit, www.turbocity.com, they offer larger injectors, and whole TBI units that are bigger to handle more displacement.

On the motor side of things, without touching the shortblock, heads, cam, and valvetrain are your best courses. A good hydraulic roller matched to a set of aluminum, smaller chamber heads to boost compression, and 400 HP is possible.

Depending on how much time is on the motor you have, a full rebuild wouldn't be a bad thing to consider, and you could even look at installing a stroker crank and make your motor a 383.  

55 GUY and GigTG are pointing you in the right direction it looks like.Don't forget about a solid transmission and around 3:42-3:73 rear gear w/posi unit,also headers are a must.Like mentioned invest in good cfm flow heads and less camshaft duration and 114-116 lobe centers for high vacuum.Already having a roller cam is to your advantage that some people don't have to make a little more streetable power.       WIEDER  

I have been looking into one of those top end kits.....do you think that would be a good idea,being that all the parts(heads,cam,intake) will already be matched up and the kit is suppose to get me around the range i was lookin for?? also my car came with the 3.42 gears already in it.......also if i purchase the top end kit,what will i have to do about the bottem end as far as crankshaft,bearings and all that other stuff  

Buying components "kits" is always a good way to save money and save some hassle. Taking it the farthest is just to go buy a cheap crate engine.

If you go with the top-end kit you need to make sure that the bottom end is in good enough condition to support the extra power. As you put more pressure and heat to the rings they may be more apt to leak more if they're already heavily used. Rotational speed and tension forces are also going to increase on the bearings...

More than likely though you will see good gains with your bolt-on additions unless the engine is very tired.