Mufflers?

[jaslo]

Just recently installed a K&N FIPK on my truck. Has the 4.8 V-8. Just wondering if I should replace the stock muffler or not. Thinking of putting a flowmaster on in place of the stock muffler and leave it that way or is dual exhaust better. But I dont want to lose the low end power since I do tow a trailer once in a while. And I also dont want to lose fuel mileage. Anybody have any ideas?

[Chris97K1500]

I changed just the stock muffler to a Borla and kept the rest all stock, except for the Borla intercooled tip. I love it, probably not the best performance that I'd get with a complete cat-back, but since I could do it myself and already had the Borla muffler, it was cheaper for me. My wife and baby didn't want the cab to be too loud, so the Borla worked best for me. There are many good quality mufflers out there, really just depends on how loud you want it. I'd probably gone with a Flowmaster 50 series, not as loud as the 40. Chris

[bigtruck21]

I've got the same problem. I haven't seen any proof that the aftermarket mufflers or catback systems increase hp and tq in the entire rpm range. Seems like everyone has a top end increase over stock, but at a cost of low end torque. Gibson has been the closest saying they tune from 2-4k rpms instead of 3-6k like other companies....but I've heard two guys say now that their gibson systems didn't increase performance. Also heard magnaflow loses low end tq. Borla fell apart on one guy, resonated on another, and made no increase for a third. Flowmaster is loud and no gain according to 2 people. It's pretty sad you can't get honest info from manufacturers. I want something tuned from 1k-4k rpm with better hp, tq, and gas mileage and a good sound, but I won't change from stock until I'm confident something will.

[Shaners]

For a light rumble and very little resonance and still enough back pressure to keep your Vortech spunky in the low RPM's, You might want to consider the 70 Series from Flowmaster....

[Black02Silverado]

For a light rumble and very little resonance and still enough back pressure to keep your Vortech spunky in the low RPM's, You might want to consider the 70 Series from Flowmaster....

I called up Flowmaster to ask them about their cat back system and the individual I spoke with told me to save the money and use it for my truck payment and just replace the stock muffler. He said that there isn't any performance gains between the cat back and if I just did the muffler replacement. The only difference would be dual exhaust looks with their catback.

 

So I went and bought their 70 series big block muffler. It has just enough rumble to know it isn't the stock muffler but no inside cab loudness at all. I really like it.

 

Now did I get a performance gain? Don't really know. I didn't loose anything, nor did I see any improvement. I do like the sound and it is my piece of mind that I might get some kind of gain out of it.

 

I was surprised when Flowmaster themselves told me to just get the muffler and save the extra cash for my truck payment. Most would want you to spend the money.

 

The muffler was a direct fit, ran me $115 from Summit 18 months ago and cost me $20 to have the local muffler shop weld it on.

 

To me it was well worth it.

[silversport]

Love my Corsa, love the Pro-Tips and love that it's GM approved...

[jaslo]

Does anyone have the flowmaster 70 series on their trucks? Also I have noticed that the truck is gulping more gas. I know I have had the K&N FIPK on for only about 400 miles, but should I be getting better or worse gas mileage?

[rtbrick]

I wouldn't worry so much about horsepower or gas mileage gains or losses as I would about the exhaust note itself (you bought your truck because you liked it, not because of the "great" gas mileage or high horsepower).

The Chevrolets seem to be rather quite from the factory (just listen to the Dodge fullsize) and it may be the customer base Chevrolet is targeting. In any case, if you like quite, stay with the stock setup. Otherwise you can choose a muffler that produces the level of grumble you like. I went with Gibson as I did not want too much noise in the cab. In hindsight, I think I would have liked a little bit louder, but the Gibson is fine.

[bigtruck21]

I wouldn't worry so much about horsepower or gas mileage gains or losses

I would

 

Why spend this amount of money on a noisemaker and lose mpg and get up and go? For that matter get a horn that plays a tune, or a nice aftermarket stereo that you can play a cd of someone reving an engine with nice pipes on it. Don't get me wrong...I want sound and performance too. On my harley, the vance and hines pipes were a nice addition for the best of both. Why can't any aftermarket company improve this area?

[Nick2000Gmc]

I have the drop in K&N filter and I am curious about the 70 series too. I know I get better mileage myself ( I would say a mpg or so, I'm from canada and it's km/litre). I drive hard with a heavy foot though and most people that just drive slow won't see a difference. I find the truck holds a gear better when going up hills and seems to just be more responsive. I am curious what all you guys think of the 70 series and if you found a difference in mileage and what you thought of it.

 

 

2000 GMC Sierra ext cab 5.3l 4x4 3.73

[Kania2k1]

I got the Amreican thunder exhaust kit from Flowmaster. Got it from Jegs. I think it comes with a 50 series in it. I usually drive arounf with the tow/haul mode on. Yeah it shoots my milage to he!!, but it sounds nice. I didn't notice any losses in torque, and not much in horses. I was pulling the boat and jet skiis out of the water a couple weeks ago, and it pulled just like it did before the swap. It's really simple to do, if you can get the trucks rear end high enough to fully extend the rear springs, and slide out the exhaust. I'd probably get the muffler on it's own, and if you like the sound, have a local muffler shop change the rest.

[Shaners]

I've heard the 70 series before, and the guy that has it on his stepside really likes it... It sounds stock at the red light, but has a nice rumble under power.

[ShortCrew]

I replaced my stock muffler with a Magnaflow (dual 3" in, single 4" out). The truck feels more responsive between 1000-2000 rmps. Top is harder to tell but since the muffler is straight through, I doubt you could possibly loose top end with it.

 

The sound is awesome. Really deep (probably doesn't hurt that I have the 8.1L) but very quiet. With the windows up driving on the freeway, I cant hear it.

 

I would defiantely do this again. Its much less than the cost of the catback system and I think you gain every bit as much.

[redchev]

I just installed the American thunder pipes on my truck. It came with the 70 series muffler and split rear with stainless tips. Its a little quieter than I thought it would be. Nice start up, good rumble on acceleration, and not too much noise in cab. It was a very easy install, everything fit as told in the instructions, no cutting or drilling.