I'm looking for some feedback from people with V8 engines that have two 2-chamber Flowmasters on their truck. I'm about to take my truck in ('98 Z71) to get two 2-chamber Flowmasters installed. My main question is how loud is 2 Flowmasters going to be? Would having two Flowmaster even be louder than having just one? Thanks for any information.
Your neighbors will definetly know when your are coming and going. The flowmasters produce a distinct low frequency rumble. My buddy had dual flowmasters on his 78, and I knew when he was in the neighborhood. I had a flowmaster on my 87 IROC that was much quieter because I didn't have headers and still had the stock catalytic converter. When I originally bought my Jimmy it originally had the exhaust exiting the rear with the tips pointed towards the ground and it was much quieter than it is now both inside and outside the truck. The guy that is going to do my exhaust told me that having the pipes exit the rear of the vehicle with the tips pointing down and slightly towards each other will cancel out some exhaust notes and make it much quieter.
<font color=purple> My '90 GMC had the exhaust replaced somewhere along the line by a previous owner with a single outlet 3" pipe. When that muffler went bad, I bought a Flowmaster from Jegs with the correct inlet/outlet spacing & it was about $60 - it was NOT the one recommended for my truck. 16" long & I can't remember how many chambers it was or what part # it is. It replaced a 22" muffler, so a short extension pipe had to be added between the cat & the muffler. I picked up about 1/2 MPG & only a slight rumble. Wish I could tell you which model that muffler was 'cause I'm real happy with it. </font color=purple>
My buddy has a single in, dual out two chamber on his '90, and it sounds sweet. I bit loud, but not obnoxious. His truck is a shortbed reg. cab, though, so if your truck is longer, it will probably be a bit quieter with the same configuration due to longer pipes. I would go with that setup if I had a Chevy - costs less too, with only one muff to buy.
I have dual Exhauset with 2 chambers. I noticed a great power improvement when installed on a Blazer. I love the sound from the outside! The post about the tip direction is very true. I have a bud that has same set on his truck but with turn downs and the volume is much lower. Now what I dislike is they droan. Now I don't have a H pipe installed or Cats. The cats will be on very soon. Now the droan may not be a problem with a trucks if the mufflers are located under the bed. I'll post back when the cats are on with more comments
I have a 3" single inlet/outlet Flowmaster with 3" high-flow cat, basically 3" exhaust from y-pipe back, no headers on a 90 K5 and get a nice rumble, not to load but sounds great. Here is what I found when I called about 6 or 7 exhaust shops, keep in mind this is for a newer truck with a cat (best performance is duel exhaust with no cats), they all said about the same thing - single Flowmaster with 3" exhaust will produce a little more power than 2-1/2" duel muffs but will be a little quieter. The duel 2-1/2" muff will produce a slightly loader tone with slightly less performance. I think this is due to the flow of the exhaust being forced into one pipe and then re-routed back into two again. Long story short - performance, go with the 3" single, for sound and appearance go with the duel 2-1/2".