Unless you are going to add heads, new cams and an intake manifold
do not waste your money on exhaust systems.
Want a louder exhaust, use turbo mufflers.
The stock engines on these heaps are so limp, a Honda with a fart can gives MN12's a run for their money.
If you want 1/4 mile times to drop like a rock, 3500+ stall and 3.73 gears.
Of course this is all N/A.
Forced induction is not my style.
Also my junk has long tubes, by Sean Highland Motorsports.
They still have a pair, brand new.
While I agree with the accuracy of your statement, I disagree with the idea that it's worthless.
My car is a toy, a hobby, and is the lowest priority on spending money behind my home/groceries/wife/daughter/pets/entertainment. That said, I tend to start small and build up as money permits. So, a dual exhaust would be one of the first things I buy if I were starting with a car without, as it is relatively inexpensive, easy enough to do in the garage, and is a good "supporting mod" to everything else that comes later.
I am of the opinion that building a good supporting platform first is more important than starting with the big stuff like engine/transmission. So, Exhaust, suspension, wheels/tires/brakes, rear end, driveshaft, transmission/torque converter, then engine is the order I go in. I want to do jobs once, and do the entire job if I can, before moving onto the next thing. So, if I'm going to do an engine (which I'm doing now), I'm going to go as far with it as I can afford, in as short a time as possible so that I don't get tired of not driving my car.
Everyone has different priorities, but putting a free-flowing exhaust on the car can do nothing but help, and helps build a better baseline for when you do more stuff in the future in my opinion.
97 Thunderbird LX (The GT Bird)
2003 Explorer WAP block with Modular Head Shop "street ported" heads and Stage 2 PI NA cams, 75mm Accufab throttle body, C&L upper intake plenum, Kooks 1.75" primary/3" collector headers, 2.5" full exhaust with mid mount Magnaflow dual in/out muffler, 24lb/hr injectors, 80mm MAF, Tuning from Don @ www.lasotaracing.com
, CAI that feeds from fenderwell. Jmod, 3.73:1 TL in Mark VIII carrier, Mark VIII aluminum LCAs, 93 Mark VIII driveshaft, PBR brakes (soon to be Cobras), 18x9 wheels with 35mm offset, 255/40/ZR18 Tires, Front and Rear strut/shock bracing, GR-2 shocks, Eibach 1.5" springs, 1989 SC front and rear sway bars.