crossy,

Don't expect to feel or see even on a dyno unless you can guarantee the exact same run set up each and every time the HP gains from an exhaust system. Plus remember you're pushing an 8000 LB load too, so 15-20 HP isn't gonna hit you liek it does ona 3500 LB car! Get the MBRP performance replacement muffler and then add the cat test pipe if you off road or race only of course. You'll drop EGT's which allows you to use more of the HP you have and you'll also get a quicker spool up on the turbo too! There is HP there but it'll be hard to feel especially since you added electronic HP first!

Mark @ DPPI

 

Just too add to what other people are saying....you wont see any REAL gains. But your egt's will be cooler, and spool up will be faster....that means the ECM or box that fuels based on boost, will give you full fuel faster, so instead of having 280 RWHP @2900 rpm, it may be 280 RWHP@2600-2900 RPM!! Which may not show on the seat of pants meter, but in the 1/4 mile that could mean a 1/4 second!!

 

Diesel Power Magazine March 2006 pg 138. A stock 2005 CTD gets a Magnaflow turbo back system. Cat deleted with Magnaflow 24" flow thru muffler. Dyno showed 17 more horse and 20.5 lb-ft more torque. The new system was 5" , and no mention of EGT's. They did mention that good spool- up and sufficient backpressure for quick spool-up were maintained.
Cheers
Mike
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thanks mike, thats really all i needed to see. I really didn't want to drop the cat but what has to be has to be . I guess Mark @ DPPI can chime back in and let us know but I'm betting the MBRP is more like the NELSON 51" in length, but I would also bet that there is no significant loss of flow in a longer,straight-through muffler just better muffling capabilities . It's been a while since i woke the neighbors at 5:30 AM (got rid of the 4"straight-piped 95 CTD over 10 months ago.) .
From what I've read already here and other places. there is no reason ,or benefits to running a 5" system with my mods. My mods will stop here. well maybe a better intercooler but i doubt it. thanx guys, DAVE

UNDERSTOOD- FASTER SPOOL UP, COOLER EGTs, NO LOW END LOSS IF USING SOME SORT OF GOOD MUFFLER,15-20 HP GAIN IF DROPPING THE CAT AT SAME TIME, SOME E.T. IMPROVEMENT, BUT HARD TO FEEL IN LAND YACHT.

 

Dave
Considering my sig., a 5" is not necessary. I know first hand because I just switched back to a 4" from the 5" I had. True lower EGT's, true quicker cool down, true a very tiny mileage improvement over 4" (over 22 highway hand calc). However, the lack of low end torque and spool up due to nearly no backpressure was the nail in the coffin for the 5" system. And the NOISE,.....just too much to deal with all the time. Constantly setting off my neighbors' car alarms. And the noise when I opened the rear slider was bad!

So, now with a 4" T-304 stainless turbo back system I get lightning fast spool up lower EGT's (about 100 deg all around over stock), and 21+ mpg highway, I'm gonna be alright!!
Cheers
Mike
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