Re: Cams Benefit? w/o SC?
Mild Cams by themselves don't necessarily give a significant performance increase unless, as Newline stated above, they are coupled with better intake & exhaust setups along with better cylinder heads. The more aggressive the cam, the more aggressive the performance gains.
The Ford Racing Hot Rods cams are very mild & still use all the factor valve springs, lifters and all that, so the cams by itself won't do a whole lot to improve performance. However, with new intake + manifold, new headers, and new cylinder heads you'd be looking at a pretty large performance gain from the whole package.
However, that's not necessarily the biggest "bang for the buck" option on S197 cars because by the time you pay for all those parts, you've invested probably 80% of the cost that you could have with a T/C or S/C which have a lot more power potential.
N/A 4.6's max out right around the 400 rwhp mark with a very aggressive setup; those are pretty rare to find and have had a lot of time put into their setup. I'd guess with the FRPP cams, full intake, full exhaust & heads you'd be looking around 350-360 rwhp for roughly $5-6K worth of parts & labor. S/C or T/C with labor and dyno time can be can for $7-8K (or less) with a safe potential of 450 rwhp on stock internals. The limits are much higher once you start building the motor.
'05 GT - Borla Catback, JLT Series 3 Intake & SCT SF3 Tuner, Koni Adjustable Shocks/Struts, H&R Race Springs, Roush Shifter, Hawk HP+ Brakes all around, Steeda Front Sway Bar & End-Links, Royal Purple Fluids
'2011 F-250 Super Duty Crew Cab - 6.7L PSD 4x4