Magnaflow Dual Reduces Throttle Resp?

TheKog · 08-13-2004, 10:38 AM

I had a Magnaflow dual installed a week ago or so and I've noticed a definite reduction in throttle response. Is this normal for a freer flowing exhaust system? (It does sound great -- not too loud either)

I notice the reduction in that for a given amount of throttle I turn about 400 more rpms than previously and it feels lacking at the low end of the curve.

Also my MPG has gone down the toilet from 13-14 to 10-11.5.

I'm considering adding the K&N 77 package -- currently the intake and filter are stock.

Thanks in advance for any thoughts. My truck is a crew cab and I don;t drive with a lead foot.

juma · 08-13-2004, 11:33 AM

Quote:

Originally Posted by TheKog

I had a Magnaflow dual installed a week ago or so and I've noticed a definite reduction in throttle response. Is this normal for a freer flowing exhaust system? (It does sound great -- not too loud either)

I notice the reduction in that for a given amount of throttle I turn about 400 more rpms than previously and it feels lacking at the low end of the curve.

Also my MPG has gone down the toilet from 13-14 to 10-11.5.

I'm considering adding the K&N 77 package -- currently the intake and filter are stock.

Thanks in advance for any thoughts. My truck is a crew cab and I don;t drive with a lead foot.

I'd give it more time to adjust. my gibby took a couple of weeks to get strong again. supposedly, you can speed this by disconnecting the battery ground overnite. juma

hellbound F150 · 08-13-2004, 01:11 PM

Just a few bits of info for you. Depending on the type of exhaust and vehicle, ALOT of aftermarket "better" flowing systems actually reduce low end torque on vehicles. In most cases you need to retain backpressure to keep torque. Also, from my experience...an aftermarket exhaust is virtually pointless unless you incorporate in intake system with it. It isnt like the old vehicles as they had no intake system anyway. They were basically pulling in as much air as possible...aside from a ram air which did nothing up until about 60mph.

The more you put in, the more you have to take out...and vice versa. Add an intake and I bet it will come alive.

LikeaRock14 · 08-13-2004, 01:58 PM

Hey hey now, it's not totally worthless!!!!! A lot of us get exhaust for the sound!!!

A majority of people notice a loss lof low end with an afteramarket exhaust. I didn't but take into consideration that's with a 454

Headers, Cats, etc, it won't help increase power a whole lot w/ a stock muffler, since you're not allowing those devices to do their job with a stock muffler holding up all those cfm's. Install a free flowing muffler, you'll see a significant gain, even without headers, cats, etc.
You won't alter the power curve a bunch with just an exhaust, but ebnough to where it's fairly noticeable.

The best thing you can do is let the engine breath, so an intake and new exhaust is a good starting point, then other things such as a tb spacer, aft. intake manifold (they're available for some GM apps. at least), etc.

smoketitan · 08-13-2004, 01:59 PM

just get a volant-or k&n, did you get an xpipe??

Jewelhunter · 08-15-2004, 09:51 PM

Quote:

Originally Posted by TheKog

I had a Magnaflow dual installed a week ago or so and I've noticed a definite reduction in throttle response. Is this normal for a freer flowing exhaust system? (It does sound great -- not too loud either)

I notice the reduction in that for a given amount of throttle I turn about 400 more rpms than previously and it feels lacking at the low end of the curve.

Also my MPG has gone down the toilet from 13-14 to 10-11.5.

I'm considering adding the K&N 77 package -- currently the intake and filter are stock.

Thanks in advance for any thoughts. My truck is a crew cab and I don;t drive with a lead foot.

This is very puzzling. I have would like to know your set up. I have duals with 2.25" pipes and the MagnaFlow x-pipe 2 in/2 out. I also have the K&N Hi Flow panel. However I got increased throttle response, and my curent mpg is around 16.5 in the city.

AlexAtMyNismo · 08-16-2004, 12:12 PM

go with the volant intake with air box..... best bang for the buck by far...

-Alex B

TheKog · 08-16-2004, 06:30 PM

I got a relatively conservative Magnaflow muffler -- I don't think it's an xpipe. It also may be that my ECU needs more time to adjust. Others have said they had reduced torque at the low end of the curve also with just an exhaust, although a minor HP boost above 4000 rpm (LOL I never run it up there ;-) I'm hoping Hellbound is right.

Other locals with big tow are also getting 12-13 at best in their crew cab Titans. I'm wondering if some of these great MPG reports up here are more the exception than the rule. Only 500 miles on the car so far.

I just ordered my K&N 77 intake kit from http://www.fox-performance.com/ -- I think the $240 was a decent price. I can't wait to get it in -- thankfully I have a cool dealer and they are going to do the install ;-) The parts manager drives a Titan so they're pretty cool about after market work. They are selling units with exhaust upgrades as well.