+1 i have it no problems at all

 

All are the same IMO

 

[/align][/align]+1, they pretty much are--here's Accufab's flow data (about 1/2 way down the page).[/align][/align]An n/a 4.6L engine can only suck in 528 cfm at 6500 rpm and 100% volumetric efficiency, if we assume 85% VE (which is on the high side) then the maximum possible requirement is 448 cfm. If you look at the flow data for the OEM setup you'll see that it max's out @ 460 cfm, at a pressure differential of 28 inH2O (2 inHg)--which is just about WOT on an n/a engine.[/align][/align]This means that there is no headroom at high engine speeds and WOT, and inrush when you nail it is limited (that's where the "better throttle response" people speak of comes from). It also means that there isn'tTHAT much room for improvement, other than response.[/align][/align]The OEM plenum with a 70 or 75 mm TB will get up to 490 cfm providing some headroom, and any aftermarket combination will flow 590-630 cfm which is more than enough to satisfy the engine at WOT and high speed; and provide good inrush capacity when you first nail it.[/align][/align]

 

so is it fair to say that a tb/plenum is a good supporting mod after you do exhaust?

 

[/align][/align]Absolutely, the factory exhaust is the least performance friendly system on the car.[/align][/align]But question #1 is"Are you planning on buying, and learning to properly use, a tuning device?"[/align][/align]If Yes, then buy it first--SCT XCal if you want a standalone device, or the Sniper Special Forces package for a PC/interface box solution (much more versatile, but also more hassle as all tuning is done on the desktop PC/notebook). Load up a premium fuel tune, you'll only get 5-7 HP peak, but you will also get 5-15 HP in the 2500 to 4000 rpm range which will make the car much more drivable and fun to drive.[/align][/align]Then do exhaust, plenum, and TB (in that order); if you bought the tuner play with it between changes, tweaking the canned tune--if not then you might want to pay for a good tune at this point.[/align][/align]If you plan on staying n/a then the only meaningful bolt-on engine mod left is cams (I'll assume you've done rear-end gears by now if you have any interest in them at all...)[/align][/align]The more expensive aftermarket CAIs and intakes can provide modest gains. Nothing that will knock your socks off but a happier engine nonetheless--if you don't want to spend around $200+ on an intake then don't bother, the OEM intake is a CAI and not a bad one at that. The el-cheapo intakes from eBay come with really crappy filters that often fall apart (inside the fenderwell where you can't see it), and will not increase anything other then intake noise. In fact, mostmade ofstraight-wall tubing are not as good as the stock intake.[/align][/align]My $0.02 worth...[/align]