Is BIGGER better, or?

[DA BIG ONE]

Would like feedback from those of you who are using 4.0" exhausts on 6.5td's.

[GMC Hauler]

Would like feedback from those of you who are using 4.0" exhausts on 6.5td's.
I have the pinnacle exhaust. The instructions arent all that great, but after scratching my head for an hour, I fit it together without any problems. Some people have had problems with the hangers, but i didn't really have any.

4.0" is the largest I would go. it fits snug near the frame. I haven't had any problems since installation.

I doubt I would notice any difference between the 3.5" and 4.0" in performance.

Pinnacle is about the cheapest, too. After 2 years, i only have a few surface rust on a few spots. They warranty all of it, too, as long as you own it.

I'd buy it again if I had to. I'll be buying one for my Dodge soon.

[wthif]

I used to run just a down-pipe :D on my truck until all my neighbors could only manage to give me dirty looks. I installed a custom 4" system on my truck; starts out as 3" and steps up to 4" around the transfer case. The only difference I noticed when I installed it was a much quieter truck and I couldn't really hear the turbo anymore. The power wasn't affected to the point where I felt it. So I can't answer your question, is 4 better than 3.5 or 3, but can tell you I doubt there is any improvement above 4" for our engines. It looks huge when you take the time to look at it and if I had to guess the exhaust tone is lower with the 4" pipe.

Funny thing is the cops didn't seem to care when it was just a down-pipe. I accidently went full-throttle by a cop with his window down a couple of summers ago, doing more wrong than just loud exhaust and he didn't even seem to care.

[signgrafix]

I also have the pinnacle exhaust. The fuel mileage went up about 1 mpg. But, I replaced the stock system AND removed the cat. It starts qicker now and I no longer have a bunch of smoke on start up. I would have no problem purchasing a system from them again. I am alos statisfied with the noise or lack of.

[DennisG01]

I also have the 4" Pinnacle. As said above, there probably isn't any performance difference between it and a 3.5". They both use a 3" downpipe. Mine didn't fit correctly when I first got it. But, after two more pieces were sent, it fits nicely. I'm happy with it. But, ifyou can get a better a deal on a 3.5" - get it - you won't be missing anything.

[jon6.5]

i had a kit put i my truck but we got rid of the Cat ( it was 70% plugged) and had a proformance fuffler put on, over stock i felt a great increase in power and the sound is perfect. A healthy grunt when you get on it but it dosent drive you batty going down the free way. In my opnion Thats the first thing that should be done, and ditch the Cat.

[baddiesel]

i have a 4" from warpspeed $318.00 delivered with a 3"downpipe and all hangers and love it,it sounds nice truck pulls better and temps stay in check now . you want to get the stock downpipe off no matter what size you go with you won't really see any performance difference between 3".5 & 4" exept the 4" sound a little deeper either one will wake your turbo up