I love turbos on 4 cylinder high reving light cars. BUT you are leaving off the larger fuel pump, injectors, fuel rail, water and oil lines, intercooler and of course a new computer to run all these things properly. Your stock driveline won't handle this kind of power either.
Why wouldn't you just go to nitrous or a supercharger for the same net lowend/midrange HP and less money? You can install a supercharger with underdrive pulleys in a day that is compatible with your existing systems. And there are no lag or heat issues. If you want the car faster remove weight.
To do this turbo thing right you have to lower the compression to allow for the high pressures up to 20psi developed with a big turbo(s). You need better heads, headgasket, pistons, rods, crank, oil cooler and a really strong block to do this. A stock block and headgasket can only reliably handle 6psi boost.
You must have way too much money.
Let's not forget other misc items such as couplers, clamps, fasteners etc.
In the short term, it's tough to beat the bang for the buck when it comes to nitrous. A supercharger though is going to cost a bit more and will not come with common turbo items such as an intercooler or good BOV. Also, unless your talking about a KB supercharger…a centri is not going to even come close to touching the low end on a turbo. Plus they come with the disadvantage of putting extra stress on the snout of the crank…and also rob more h/p than a turbo setup.
As far as lag goes…a properly sized turbo is not going to have much at all. I for example reach full boost by 2500 rpm and hold it until redline. A centri supercharger is not going to reach full boost until redline and will not produce nearly the "fat" h/p and torque curve of a proper turbo setup. While underhood temps may increase a bit…as long as your cooling system is up to par (fresh fluids, non corroded radiator) it's a non-issue.
There is no need to lower the compression for a stock 5.0 block…nor is there any need to run 20psi of boost. Any decent h/c/I turbo setup is going to be running block splitting horsepower (500rwhp) with relatively low boost levels (~10psi or less). Although new headgaskets and head studs are greatly recommended…the stock internals will hold the boost just fine. An oil cooler really isn't necessary…but can be beneficial even without a turbo setup.
FYI, the stock block is not limited by boost…but by the stress associated with torque and rpm. There are plenty of guys running 12psi+ of boost on stock longblocks laying down great numbers (400+rwhp).
One more tidbit of info…I pieced together my own kit for ~ $1700 including MAF and injectors. Sure the turbo's were used, but a they worked great none the less. You just have to be frugal and keep an eye out of good deals.
He needs to go really slow or have very deep pockets.
