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I think one could lose low end power very easily by going too large, especially adding headers and a free flowing exhaust.


This is what exactly happened to me when I put the high flow Downey muffler on, after the headers and the highflow cat, and the exhaust valves are stock. I have plenty of power at 3200 and above, but the low end torque is gone. The loss of low end torque I experienced w/the highflow muffler may not be felt much in a stock weight truck, however with mine pushing 5000-5300 lbs it made a difference. I have noticed the hills I could climb in 5th at 2800 rpm's(with my stock muffler with rust holes), I now have to shift into 4th. I haven't gotten around to putting on a less performance muffler, so I cannot say for sure that the muffler is the cause, but I am pretty confident it is. Do any of you have an idea of a muffler that has more flow than stock, but not as much as an open one, with a nice mellow tone for out on the trail?

More than tread lightly. Leave it like you were never there, nor anyone else.
'90 X-cab 4.88's 33 BFG AT's, rr ARB, Headers, Ignition upgrade, cold air induction.
'91 X-cab 5.29's 315's BFG MT's, rr ARB, custom bumper and flatbed