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Increasing tow capacity

Would installing a cat-back system to a 2004 Toyota Tundra V8 4.7 increase its towing capacity? Any suggestions for increasing capacity outside of buying a new truck?

Nothing you add should increase your tow capacity beyond manufacturers recommended max. It may enhance performance within designated limits, but unless you’re enhancing performance of the entire system as well suspension components, transmission, motor etc. you’re asking for trouble. Just adding a few HP doesn’t cut it…if that’s what you’re doing.
Buy a new truck !

Not likely. Towing capacity has more to do with the weight of the vehicle, the brakes and the suspension. A vehicle like the Dodge Dakota with the Hemi V8 has a lot of power but it’s towing capacity is limited by it’s size. A large travel trailer or boat will throw it all over the road even if it’s equipped with a 4 way sway system. If you want to tow anything with a lot of weight you need a full size pickup. There are no short-cuts.

More power helps in towing, but there is much more to consider. Most towing packages include a larger transmission cooler, a larger radiator, a bigger alternator, an oil cooler, and sometimes beefed up suspension parts.

The greater strain of towing creates more heat and more cooling to all the critical fluids is important to keeping the transmission and motor cooler and lasting longer.

If you are at or over the towing capacity for your Tundra you might need another truck with a factory tow package.

technically, the Tundra is a full sized truck. But it’s capacity is limited to 6500 for the quad cab, 7100 for ext. cab and 7200 for regular cab for the 4.7L v8, according to edmunds.
So, to increase towing capacity, you’ll need a more heavy duty frame, heavy duty suspension, better brakes, higher output engine, heavier duty transmission, oil and transmission cooler lines, larger radiator and fans, heavier duty driveshaft and axles. Price this compared to the price of a new truck designed to tow more weight(i.e. diesel).

technically, the Tundra is a full sized truck.

That’s true but the domestic versions of the full size truck (Ford, Chevy and Dodge) are larger than the Toyota. A good rule of thumb for towing is that the towed vehicle needs to be only 75% of the tow vehicle weight. That makes the true towing capacity of a Tundra at around 3000 lbs which is far more realistic than the stated 6500-7200 lbs. A 4000 lb Tundra would never be able to stop a 7200 lb load at speed. That would be a jack-knife situation of the worst kind. I think it’s criminal that certain vehicle manufacturers inflate their tow capacity.

Whatever you do, don’t forget about trailer brakes. Towing anything of any size with any vehicle decreases the maneuverability of your vehicle/rig and trailer brakes, especially with a larger trailer will help to offset the increased possibility of trouble.

I hear you. Auto corporations (as do many others) make a lot of claims to increase their profit, while putting the potential buyer at risk. I am equally shocked that potential buyers actually believe claims made by them whether the car/truck is new or 25 years old. Both the buyer and the seller are often equally blind to safety when it comes to saving or making a buck.