It's my opinion but I'd recommend Needswings any day over TVT. I've dealt with both and I can say that I've been 100% satisfied with Rob @ Needswings. Can't say the same for TVT. Rob will tell you what the product you're looking at buying will do and has the data to back it up. TVT has never posted a dyno sheet for a single product he has sold. He's always going to the dyno tomorrow if you know what I mean.
As for the injectors, there is nothing special happening and you don't just take them apart and change the internals to your liking. A select few companies can do this with their proprietary injectors but not TVT. He's sourcing the injectors from a distributor just the same as I or anyone else would. As for going with the biggest you can get, it won't make you more power but rather will do just the opposite and worst case, you run the risk of washing the cylinder walls and wrecking the engine. If you want to go with a slightly larger injector, you'd want to stick with something that is just a bump higher than stock. Remember that when you're looking at injector data, they are measured at 43.5 psi but our fuel systems run at 55.1 psi so that number is actually higher. The N/A stock injector data is 15.1 lbs/hr @ 43.5 psi which is equivalent to 17.0 lbs/hr @ 55.1 psi. The 5.0L V8 injector data is 18.75 lbs/hr @ 43.5 psi so if you do the math, it's aproximately 21.5 lbs/hr @55.1 psi which is a 26% increase in flow. In my opinion, this is too great a change. You're not running out of injector so there is no reason to change them. A tune will get them to where they need to be. Again, NeedsWings will get you taken care of in this department.
On to the fuel pump, they're the same between the N/A and the SRT6. If it will handle the needs of our injectors stock, there is no way you're gonna run into any problems with yours. If you feel the absolute need to buy a fuel pump just to say you did, get ahold of NeedsWings and tell him I'd like a walbro setup. He has my address. LOL I'll send you a nice little card and think of you every time I start my car.
BTW, that was meant as a save your money statement.
Now on to the 80mm throttle body. Go big or go home right? WRONG! First off, the intake manifold isn't designed to for it so it would be the equivalent of running water through a fire hose but at the end of it, you've got a regular garden hose nozzle. Second, the intake manifold isn't designed for it so you'd have to machine out a larger opening, machine new mounting holes and then pray to god you got it all right and have no leaks. The 74mm is a great choice because not only will all your existing parts work with it, the intake manifold is actually designed for it and the two mate up perfectly. Just be sure to use a new TB gasket when you install the new one. The MB part number is A 112 141 13 80.
As for the race exhaust, just go with a magnaflow cat-back system if you want to mess with the exhaust. You might pick up a little power but exhaust mods aren't very drastic on these cars so no need to go with something off the wall. Lots of people have the magnaflows and are very happy with the way they sound and perform. You can even weld on the factory tips if you don't want it to look aftermarket.
Lastly, there is no need to go with the larger V8 MAF housing. You can save a few pennies by not buying it as the NeedsWings dual CAI comes with a matched MAF pipe. Part of the kit, tested and works like a charm just like the rest of his products. He has data to show how much better they flow compared to any other intake out there as well.
I know I've thrown out NeedsWings a lot in this post and a few of you are probably thinking I'm one of his nut swingers but the guy really does put a lot of time and money into making sure his products work and actually do what they advertise. He's also there if you run into troubles and need help with something. There is nothing he sells that he doesn't stand behind and if you need it, he either has it in stock or can make it/get it in stock as fast as anyone out there. Honestly, your best bet is to get in touch with Rob @ NeedsWings and talk over your plans and see what he can do to help you achieve them.