unfortuantely, it will NOT fit directly without some machine shop work. The flange bolts won't align directly and you need to slot the holes on the IM for them to align up to the holes on your LS head. Secondly, the oil and coolant passages don't align and so the shop has to weld shut or reshape the passages to align with your head's passages...or else you'll get major leaks. I'm not trying to discourage you from doing it but you have a couple of other things that get in the way:
1. you will need the IAB solenoid valve system off the GSR to activate and open the secondary butterfly valves on the IM.
2. you will need the GSR ECU to give the command as to when the secondary valves should activate (based upon the IAB's vacuum pressure).
What are the benefits? The 2 stage or dual IM has a bigger plenum than your LS single stage IM and has more flow capacity when all 8 runners are open...so you will get gains up top. Secondly, it is a 2 stage IM. So in the lower rpms before the secondary valves open, you will be running on 4 longer IM runners which provide more low-midrange torque. So there are benefits. But you have to do those 3 things I mentioned for it to fit.
If you run Crower 403's with this IM it's a killer package for the street.
I suggest however you look at the Skunk2 single stage IM for your engine instead...direct bolt-on with no machine work, no IAB issues, no ECU issues. It gives up some midrange because it is a single stage IM but has gains in the upper rpms.
there really isn't one. Since the teg has a low rod ratio motor, it tends to get as much out the low end "hauling" as you can get for an all motor, low displacement 4 banger. As I say to people, you'd be far better off buying a domestic big displacement V8 if you want cheap low end hauling power. FI or ITB's (individual throttle bodies which need huge injectors and a ton of ECU reprogramming just for them to idle) are the only way to get low end gains that are meaningful on a 4 banger...and the gains are across the entire powerband.
closed IM's with plenums (not ITB's) like the ones we have stock tend to try to help the low rod ratio motor by pumping up the upper rpms where they need more help breathing.
I guess you could drop a b16a single stage IM on to get some low end gain but your top end would get choked off by a huge amount.
Your best bet to gaining more low end is advancing the timing (Honda ECU's tend to run a lot of ignition retard stock in the low end for traction purposes), cam gear tuning, using a bigger cam, boring the cylinder out, and using a long intake.
As I said IM's are part of the induction system and their runner lengths are tuned to give a certain peak torque at a certain rpm based on resonance theory (If you are interested in the topic, search under the term Helmholtz resonator and induction system on your browser search engine). They are designed to give peak power at specific location based on the cam, redline, displacement, rod ratio, and port volume.
Bigger plenums, shorter IM runners, and bigger diameter IM runners give more power at higher rpms. The width of the powerband is changed as you change these IM variables.
Remember that the IM plenum size dictates your TB overbore size.