Factory Exhaust

[BLACKTUNDRA05]

I was under the truck changing the transmission fluid and checking out the new flowmaster 40 muffler i got installed, when i noticed the tubing going from the mid pipe to the header/cats...WOW... the tubing coming from the header to the mid pipe joins by 2 pipes being crushed to fit into the mid pipe, is that efficient ? and why didnt toyota just use a Y-PIPE (mandrel bent) to join the 2, i mean i looks awful, does this hurt performance ...... sorry no pics

[Ltning/QC10nomas]

Probably flows 5 or 6 less peak HP than a mandrel piece but almost everyone who has replaced it has lost bottom end torque.
The old saying is Horsepower sells cars but Torque (and the TQ curve) is what gets a truck moving.
Some have learned that lesson the expensive way with pricey 3" free flowing exhaust that guts bottom end power on these small motors. Apparently they are not that wild about being free flowing.
Search the threads for exhaust mods and you will find all kinds of useful info.

[Big_Al1]

Suppose to help with low end torque and balance out the low to high power.Some have changed it out and gained others say they lost low end.

[BLACKTUNDRA05]

so the crimped tubing has to be there for mandatory back pressure to achieve the best low end torque ?

[Big_Al1]

basically