Maybe coming from a completely stock system I'd feel a difference but since I already had a short straight exhaust, I feel like maybe I made the wrong choice.

Why did I want a full system in the first place? When I bought the truck, it came with a short straight exhaust. The previous owner had the sytem chopped off behind the crossmember and added a piece of 4" which turned out under the rear seat. This was cool at first and I didn't mind the sound but two years later, I was looking to quiet it down. Since we have a travel trailer now, I want to be respectful to the other campers, sometimes we get into camp late. Plus you can imagine how loud it was and frankly it didn't sound good WOT.

Since my stock system was gone, I just couldn't add a muffler so I picked up a full 4" MBRP system. Installation was a breeze, much easier than I expected but upon my first test drive I noticed a drop in performance or at least perceived performance. Before, the truck felt very light on it's feet. The gas pedal was ultra sensitive and extremely responsive. It hardly took any pedal pressure to make the truck get up and go.
After the new install the truck feels alot heavier and kinda of sluggish. At first I thought it was the placebo effect being the exhaust was quieter but a second drive today confirmed it's not. It definately takes more gas pedal to get the truck to go now. It still hauls *** when I stand on it but I loved how it felt so light and nimble with hardly any pedal pressure.

Even though I now have a larger diameter exhaust, I've gained distance so I've still added back pressure. I thought it would balance out. I suppose it was enough to slow the spooling down and kill my nice responsive throttle. Isn't that was caused this, slower spooling?

Now... I know there are guys on here who say the full system is a complete waste of money and just add a muffler delete. Well it's too late for that and I couldn't do that anyway as I didn't have an exhaust system.

Short of losing the rear half of my new exhaust, how can I get my nice old crisp throttle back?

Here's my old system, it was definately a shorty.





How else can I get my

 

If You got the complete system with a muffler, You might can do a muffler delete and see what that does.

 

You didn't add back pressure you went bigger so you lost a little hence slower spool-up

 

Yeah I thought about that. It shouldn't much louder maybe more raspy. On my last F250 I just did the delete and it wasn't too bad.


I think I still added back pressure as the exhaust isn't exiting as soon as it was. It's encased all the way back to the tail pipe, that makes a difference. So you're saying back pressure increases spool up?
You said you doubt 1/2" would much much difference in another thread.


Thanks guys.

 

I didn't feel any lose in the seat of the pants feel when I changed out to the cool duals, I know the truck runs alot cooler EGT wise and sounds magnificant. What a bummer though, we ussually hear praise, sorry to hear. On a side note and maybe not related but on my old Harley from the stock exhaust I went with a straight 2 or 3 inch Pythons and lost some power, sold those and put the inch and three quarters straights on and got my power back, but thats on a gasser though, that was a back pressure issue for that senario. Sharp lookin Ex by the way.....

 

Thanks Mike, You went with duals so it opened up your exhaust, less back pressure. I closed my exhaust (in my mind) lengthwise creating a little more back pressure, maybe... IDK, maybe I'm off my rocker?
It does sound like a gasser senerio. I had a 5.0 with 2 1/2" Flowmasters and turndowns under the car. I installed 2 1/2" tail pipes and definately lost some snap.

I like the sound much better though, maybe I need a 38R and stage ones.

Are you going to make it to RRE this year?

 

more air through the system, your probably experiencing turbo surge. No backpressureis a good thing on a diesel. Back pressure tuning only applies to gas motors.

 

The 1/2" would not make much diff in HP/EGT on a stock engine. That was the question

 

Nah, turbo surge is something completely different. I had that when I towed and could even get it to surge empty. The ATS housing cured that.

Gotcha, sorry.

 

It appears your old system had no muffler? Even though your new system is larger in diameter, you have a muffler, which I feel could increase the backpressure some. Kinda at a loss as to why you lost performance though?

 

Correct, no muffler and I agree with the increased drag the muffler creates as it has louvers inside (they are facing the tailpipe BTW).

I don't know if I actually lost performance, it may just be the turbo spooling up slower and causing the throttle response to be slower as well. I think this is what's happening, can anyone verify? Like I said when I stand on it, it still takes off like a bat outta hell, builds boost fast, all that. Just feels different at the pedal.

Y'all think I'm nuts, I know.

 

Well the good side is you have it, now if you go bigger (injectors-turbo-etc) like we all seem to want to you have one thing off the list.

 

I put my exhaust system on when I still had the stock turbo and nothing out of the ordinary hear. Maybe another reason why I didn't pay to much attention is that my baby was breathing now, plus the sound factor, who knows but anybody can debate the half inch therory but when you have a "Full" mandrel bent 4 inch exhaust thru out versus 3.50 , whew, wheres Ernest Eugene when we need him, lol, not disrespecting Gene, he's our professor here. My 38R really made a big difference, period, seat of the pants feel, plus lower EGT's, the turbo whistle is just right too, under the hood and out the tailpipe, if that tickles you fancy. As far as RRE11, we'll see, it might and looks like last minute but we're working on it..

 

I had exactly the same effect when I had a 4" installed- lost back pressure, slow spool up and no snap. Very disappointing. Jody of DP Tuner told me that a 3.5" would've been better. After Jody did my live tune,even with the 4", I got it all back and much, much more.

 

I have a e99 (small turbo) and took the cat, muffler and stock exhaust pipes off installed mbrp 4' turbo back with muffler and noticed it was a little slow spooling up unless my foot was heavy into it then it moved out nicely. So I took the down pipe off and wrapped it with ThermoTec wrap 30' and that helped alittle now I would like to wrapped the exhaust side of turbo to keep it hot. And see what differents that makes before I move to next mod. Actually next mod is hutch and lift pump. My point is that hot exhaust gasses help spooling and lag. And with more air (4') lower egts but with too low of egt's you run into spooling up slower at lower rpms. Now diesels are somewhat new to me but I ran gasser turbos since the 90's and it worked on them but I have yet to prove it to myself with diesels. Something to think about.