Couple of Questions on Innercoolers and Exhaust

I have a few questions about the difference between top and front mount innercoolers and cat-back and turbo-back exhaust.

If my car has a stock top mounted innercooler, what kind of horsepower gain am i looking at if i switch to a frontmount?

What is the difference between a turbo-back exhaust and a cat-back exhaust and when is one more efficient than the other?  

If you were to switch to a front mount, you could possibly gain 5+ hp, or you may lose a few hp all depending on the design of the intercooler. Most companies do their R&D so you shouldn't have to worry about losing any hp if you go with a reputable manufacturer.

Turbo-back and cat-back/after-cat are pretty much self-explanatory. Turbo-back exhausts are pretty much any exhaust that replaces the downpipe, cat and stock exhaust piping, so pretty much the whole stock exhaust piping, right after the turbo. Cat-back exhausts only replaces the piping after the catalytic converter. Typically turbo-back exhaust will flow more efficiently, therefore creating less backpressure, thus making the engine more efficient and finally making more power, than their cat-back counter-part. That's not to say that a cat-back can't be on par with a turbo-back. The drawback with a turbo-back is that they're more expensive and you're pretty much deleting the catalytic converter.  
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http://rides.importtuner.com/ride/1076723/jimichanga/2005/honda/s2000/index.html

Then by not switching to a frontmount and saving some money would it then make it more difficult to furthur mod my car?  

What do you drive?  I assume and STI because you mentioned having a tom mount.

Leaving your TMIC won't impede your modding process.  It's just that if you go FMIC, it relocates it to the front and will give you more cooling of the charged air because of the greater surface area and more airflow.  
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"It's either a fuel injection or carbeuration problem" said the man with a 2001 Saturn Ion
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Daily: 2000 Honda Accord Coupe F23A1 VTEC
Project: 1995 Eagle Talon TSi AWD

no i drive a Mazdaspeed6 but i understand the idea of the frontmount and im debating whether or not to switch. I think ill keep the TMIC for now to save money and upgrade lader  

Wait.. your 6 has an intercooler?  I'm not educated when it comes to Mazda...  
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"It's either a fuel injection or carbeuration problem" said the man with a 2001 Saturn Ion
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Daily: 2000 Honda Accord Coupe F23A1 VTEC
Project: 1995 Eagle Talon TSi AWD

he has a mazdaspeed 6. they are turbo awd. probably the best car mazda has made. with the mazda 6, i would swap out to a fmic. unlike the sti, the 6 doesnt have a hood scoop to force mass amounts of air into the intercooler.  
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the godfather has spoken

Youre right, it doesnt have a hood scoop but it does have a channel from the grill up the underside of the hood to the top of the innercooler. It works nearly identically to a scoop yet it doesnt have the ugly hole in the top of the hood  

it doesnt work as well as a hood scoop. it doesnt give the air flow as if it were a scooped hood.  
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the godfather has spoken

Yeah you're probably right, that makes sense. I just dont like the look of a scoop for some reason.  

if you dont want the scoop look, then i would get a fmic. it will help out greatly.  
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the godfather has spoken

i want to swap my 4g64 head with the 4g63 evo 9 head now i need to know if the talon and the evo head aqre the same and also should i get new pistons and lifters rollers and all that fun stuff or should it come with. plus it being a dohc how would the crank hold up on that 4g63. need a little advice this is my first build and every one hates on DSM lol  

No one around here hates on DSMs.  *** I think I'm the only one who has one, anyway.  

First off, I don't understand what you're saying.  You say you want an Evo 9 head and then ask if the Talon and Evo head's are the same... ???????  
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"It's either a fuel injection or carbeuration problem" said the man with a 2001 Saturn Ion
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Daily: 2000 Honda Accord Coupe F23A1 VTEC
Project: 1995 Eagle Talon TSi AWD

no, they are completely different. but it matters on which 4g64 you have.if you have the 2g 4g64 then you will need the head from the gst or gsx. if you have the 3g the you will need to get the evo 8 or evo 9 head.  
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the godfather has spoken

I'm surprised they bothered with a top-mount with no hood scoop. Of course, I always assumed Front Mounts > Top Mounts. Most people I know with Subarus switch to Front Mount  
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1994 GTO Twin Turbo
nothin wrong with front-wheel drive, I just refuse to own one