I've never speced the cost on doing a full out turbo kit. If I were to plan for this, I'd estimate $2000-$3000.

If I were considering this, I'd spreadsheet a list of the parts I need, where to get then from and how much they cost. Plan extra funds as a buffer.

 

I would have to estimate much higher. You can buy a 3800 kit for that budget, but the R&D is already done.

If you are paying someone to custom build brackets and manifolds and basically do their own R&D, it's going to be very very costly. Couple that with the fact that you don't know for sure what injectors and tuning will need, that can get pretty pricey in itself.

Hey, just checking out the N-Body scene for a kit and you are looking over 4500: MMS 3100/3400/3500 Grand Am/N-body Turbo Kit - Milzy Motorsports

 

Why wouldn't I be able to buy a 3800 kit and slightly modify it to fit my engine since they aren't that different?

 

The geometry on a 3800 and 3400 is completely different. Apples and oranges.

In terms of the turbo and exhaust piping, keep in mind, the 3800 is a 90* v6 and the 3100/3400/3500 are 60* v6 (and those three and a I believe a few other GM 60 v6 engines, share an almost identical block). The easiest way to explain what I mean by 60* and 90* is it's the angle at which the pistons travel. That plays into part of the issue, such as distance from the exhaust ports on the front head to the rear.
Next, the bolt pattern and spacing of the exhaust ports and manifolds on a 3800 vs 3400 are completely different.

You would be better off buying an N-body 3400 kit and having someone resolve alignment/fitment issues (which I believe would be around the down pipe to the rest of the exhaust).

And Chibi posted a good link. Milzy is a popular vendor with the N-Body crowd (one of the few to cater to the N-Body, much like ZZP/Intense/Wbodystore cater to us W-Body guys). And the price of a ready to bolt on kit for a N-body is almost $5k before selecting options. Food for thought, at that price tag, as mentioned earlier, you could probably do a full swap (trans/engine/wiring) of a L67 3800 SuperCharged drive train with some extra mods.
Now, since Milzy has experience with the 3400 engine and both N and W cars, they might be able to assist in a turbo kit for a Monte.

The other question I don't think mentioned, were you considering to do most or all the install yourself? Or send it off?

You are still in the researching stages, there is a lot to learn (I have not dabbled with boosted engine modding, but I know the cost rises). I think Chibi can speak from experience, when you thought you had it all figured out, you may come across a couple "gotchas" (aka: need to spend more money) before it's done. Sidenote: I really wanted to follow in Chibi's foot steps on his Novi build and as he was beginning his build, I had a chance locally to buy in on the same kit (I had to draw a line on my Monte modding projects).
Also make sure when you factor in cost, you don't forget to plan for down time (anything custom or large scale, you are going to be facing risk of down time to get things dialed in right).

I suggested spreadsheeting all of this (helps build up a budget). You can make multiple spreadsheets to weigh different options to help drive what direction you want to go into.

Another option not discussed (but it was a foot note sorta in the cheap 3400 mod thread I linked earlier). Top swapping. Going back to the 60* v6 line share a lot of the same make up. 3100 owners top swapped with 3400 parts and 3400 owners have top swapped with 3500 parts. This is taking everything from the heads up and swapping it on the car, then get it re-tuned and away you go. The benefit is more air flow, more HP. If you can hit local junk yards, getting these parts from yards that let you pull them is fairly cheap. Or look into swapping the entire 3400 for a 3500.

Just some additional options. I never did any serious research on it, but I know those mods have been done. For those who know the 3500, it's drive-by-wire and I know people have replaced the throttle body with a compatible one that uses a linkage cable.

On that note, sorry for the monster amount of reading, but I hope it helps.

 

I have considered doing a swap too but the problem is that I can't find an engine with decent mileage. I found the 5.3 ls4 motor from an 06 SS for $900 but no trans or wiring to go with it

 

I still think that it would be easier to go with a 3800 swap. The Supporting parts would be readily available either thru aftermarket or the bone yards. At that point you would have to replace the final gear of the trans and/or have the ECM programmed for the new motor, but you would not have to replace the complete transmission.
You can get the 3800 n/a or the 3800 s/c and then work the trans from there. I think that would be the most cost effective way to go. One member here had to replace the seized motor in his daughters 01 LS I think it was. He was not concerned with cost so much, but he pick up a 3800 s/c with trans for $900. He replaced all the gaskets on the top of the motor and now she drives a 01 LS with 250 hp? He got the motor with the exhaust manifolds and down pipe.
Aslo, if you can find a motor, and the mileage on it is of Great Concern to you, you can always do a complete rebuild on it. But a think I saw here that T.E.P. has rebuilt 3800s for sale! So there are plenty of options for you. I think there is a lot less work involved in swapping in a 3800 than with a 5.3. But I could be wrong?

 

Mileage can be a toughy, because these cars were all driven.

Might I suggest for now, you look into simple projects. Get an intake on the car, do a cat-back exhaust, get a new downpipe put in. Get the car tuned to be a little more aggressive.

Or if you want, before the tune, you can also look into things like a larger TB and ported intake manifold for the 3400, I believe there is room for improvement there too, then get a tune.

Also those modifications (outside of the downpipe and intake) would lend themselves to helping out in the long run if you decided to still try to do a custom turbo build.

 

Hey maniac i have a 3800 series II N/A and i'm lookin for a supercharger kit for it. i know zzp sells one but UPS charges insane brokerage fees on stuff coming into canada. do you know of any company that offers this kit and uses USPS for shipping

 

Tobian just go to the junk yard and get the parts needed for a supercharger. It's way cheaper this way! Or join some of the Grand prix forums as members there sell top swap kits all the time.

 

My local junkyards have been picked clean of S/C 3800 motors. trust me ive looked