Hey guys i did a lot of searching about this and there have been a lot of debates about this topic. I would like to know from the guys that have straight pipes if it was worth it and what was gained. heck even if you don't have a straight pipe and want to put your 2cents please feel free.

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Horse Power: How fast you hit a wall.
Torque: How much of the wall you take with you.

06 CRD
OME HD w/clevis top plate
JBA 4.5 UCAs
245/75/16r Goodyear Duratrax
Fumoto Valve, V6 ABM
Rock Lizard Super Skinks
Cobra 75 WX ST
ECO GDE tune, 2.5 straight piped
ProVent, Samcoed
Non F37ed TCM
DieHard P1

we straight piped my girls libby. It sounds good, maybe a little power pick up, but the big adv to it was of that heavy stupid muffler that was on the jeep.

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2005 Jeep Wrangler Rubicon TJ- Impact Orange
4'' RK LA, 35's KM2's, Warn front bumper, Warn rear bumper with tire swing, Warn gas skid, Nth oil skid, 4.88's, Alloy axles shafts F&R, Rokmen Corner armor with led's, and Rokmen sliders, custom back-up lights from gen-right, piaa 510's, IPF green glow fatboy's up front.

The neck between the cat and muffler is a big restriction where the cross section is just over 2" ID.
I put a pressure gauge between the cat and turbo, then I ran tests before and after I installed the Magnaflo.
Then, just after I blew out the gunk plugging up the cat with a trip on the express way, the Isspro Turbo gauge showing back pressure has stayed on zero all the time.
Straight pipe or other exhaust mod will not be worth your time unless you open up the flange after the converter going into the muffler.
Your EGT will drop 150f-200f and your boost will be snappier when you need it.
Also your fuel mileage will improve with a free breathing exhaust.
Just remember to figure out your odometer error, with my 215-85-R16 ATR Coopers, I need to multiply my odometer reading by 1.115 to correct the error. With the stock 225-75-R16 tires it was 1.10.
Even with my still stock tune and Torque Converter, I blow away Tahos.

my old post: http://www.lostjeeps.com/forum/phpBB3/vie ... hp?t=45768

Good luck, but make sure what ever you do open up that choker flange

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2006 Pearl Green CRD
Magnaflow 2 1/2" Cat Back
KJ Extra Leg Room Brackets, Carter Lift Pump, V6 Airbox, ORM
Fuel cooler, Oil Separator, Progard 7
Gauges EGT Boost Trans Temp Oil Pres, Michelin LXT AT2 245 70 R16
7,000# Draw Tight hitch, PML EX Deep Trans Pan
Centrifuge, SunCoast, Transgo, RAM TCM, InMotion Stage 2
Wife's 99 TDI VW Beetle

Straight pipe does not sound significantly different from stock.

I have it this way and it seems to be the best choice. Plus it's really cheap.

My cat is gutted and i have no muffler, i have the restriction from before the flange removed as well. It's pretty mild. Much like stock, better cruise though.

I have also experimented with different lengths of pipe and tested for a hood stack. it sounds like crap. Any length of pipe that is not at least at the rear dif seems to sound bad (to me) I cut my front pipe right before the flex joint, and it sounded great, except for the drone. The turbo was GREAT, even at idle, it sounded like it was "spooled" (because it is!) however the "pressure cooker" sound of gases escaping between the fins, is very very overwhelming. I have spent about 500 dollars or so on different pipe sizes and lenghts and the truth is the mild straight pipe seems to be the best way.

I have tried 2.5 inch downturn from right before the flex joint, a 3 inch down turn in the same location (both of the ends were right AT the cross member) and the gas/pressure cooker noise is simply to loud. I wish i had recorded it on my camera.

I wanted a hood stack badly, and if we relocate the coolant and get a different size bottle, and move the heater hoses, it's doable, but it sounds bad. it's a 4-cyl.

I am open to any other options, i wish the straight pipe was louder.

Just one word of warning for exhaust system mods. Make sure to keep the flex coupling installed. This may be a restriction, but it significantly reduces the vibration and forces that are transmitted to the turbo frame. Without the flex coupling the turbo housing may crack over time, due to the added stresses from having a solid exhaust.

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Providers of wholly developed aftermarket solutions for the KJ CRD.
(248) 977 - 9531

The flex pipe does need to stay, cause of the torque produce from the turbo. it does sound cool but it is not recommended to run without one.

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2005 Jeep Wrangler Rubicon TJ- Impact Orange
4'' RK LA, 35's KM2's, Warn front bumper, Warn rear bumper with tire swing, Warn gas skid, Nth oil skid, 4.88's, Alloy axles shafts F&R, Rokmen Corner armor with led's, and Rokmen sliders, custom back-up lights from gen-right, piaa 510's, IPF green glow fatboy's up front.