ARH header install experience . . .
12-22-2010, 11:56 AM
#1
ARH header install experience . . .
Installed a set of 1 7/8" ARH headers and catted Y-pipe on my 2008 Seirra Denali this week, and here are the details . . .
First - I would have never guessed in a million years just how "rowdy" my exhaust would sound with headers! At certain RPMs and throttle openings, all he!! breaks loose (a raucous, bellowing roar is my best description) at the rear of my truck, LOL! I still have a completely stock cat-back, mind you! I'm very glad that I had not removed the resonator, as I had been considering!
That said, during normal cruise, it sounds very near stock, just a tick louder. VERY nice. Also interesting that during part throttle acceleration, say approx 1/4 to 1/3 throttle - at each upshift, when the ECM cuts fuel delivery during the upshift, there's a quite noticeable "back-rap" sound. Overall I must say that I'm pleased with the sound, though. Definitely NO cruise resonation or any other such nonsense.
As far as the performance difference, it's hard to say at this point. I suppose that the exhaust note difference makes the performance difference difficult to determine. Seems that it MAY have lost a bit of low-RPM torque, though at higher RPMs I believe there may be some improvement. To be expected, I suppose, with 1 7/8" primary tubes on a 378" engine. Admittedly, the traffic and weather yesterday afternoon and this morning have not yet allowed me to make any heavy or full throttle runs through the gears yet.
The installation was an absolute breeze. If ARH would have sent the correct Y-pipe to start with, we'd have been done in less than 3 hours. No fitment issues, excepting that the #1 and #3 tubes are EXTREMELY close to the steering shaft. Had to use a cutoff wheel to remove the protruding threads of the upper pinch bolt and part of the pinch bolt spring-steel flange nut. The battery cable to the starter solenoid had to be relocated forward. The oxygen sensor wiring all reached fine with no extensions necessary. My only fitment gripes have to do with the steering shaft intermediate shaft interference, and that the Y-pipe hangs down below the transmission crossmember just a touch.
One more BIG gripe though - on the way to the shop this morning my CEL came on. Before I even hooked up my Tech 2 to check codes, I knew what I'd find - sure enough, P0420 and P0430 catalyst efficiency codes for both banks! There's simply no way that those tiny "high-flow" cats have sufficient O2 storage capacity. Oh well - I'll just have the cat monitors "tuned out".
I have an appointment with Pat G on the 9th for a full dyno tune with wide-band. Hoping my truck is a beast after that!
First - I would have never guessed in a million years just how "rowdy" my exhaust would sound with headers! At certain RPMs and throttle openings, all he!! breaks loose (a raucous, bellowing roar is my best description) at the rear of my truck, LOL! I still have a completely stock cat-back, mind you! I'm very glad that I had not removed the resonator, as I had been considering!
That said, during normal cruise, it sounds very near stock, just a tick louder. VERY nice. Also interesting that during part throttle acceleration, say approx 1/4 to 1/3 throttle - at each upshift, when the ECM cuts fuel delivery during the upshift, there's a quite noticeable "back-rap" sound. Overall I must say that I'm pleased with the sound, though. Definitely NO cruise resonation or any other such nonsense.
As far as the performance difference, it's hard to say at this point. I suppose that the exhaust note difference makes the performance difference difficult to determine. Seems that it MAY have lost a bit of low-RPM torque, though at higher RPMs I believe there may be some improvement. To be expected, I suppose, with 1 7/8" primary tubes on a 378" engine. Admittedly, the traffic and weather yesterday afternoon and this morning have not yet allowed me to make any heavy or full throttle runs through the gears yet.
The installation was an absolute breeze. If ARH would have sent the correct Y-pipe to start with, we'd have been done in less than 3 hours. No fitment issues, excepting that the #1 and #3 tubes are EXTREMELY close to the steering shaft. Had to use a cutoff wheel to remove the protruding threads of the upper pinch bolt and part of the pinch bolt spring-steel flange nut. The battery cable to the starter solenoid had to be relocated forward. The oxygen sensor wiring all reached fine with no extensions necessary. My only fitment gripes have to do with the steering shaft intermediate shaft interference, and that the Y-pipe hangs down below the transmission crossmember just a touch.
One more BIG gripe though - on the way to the shop this morning my CEL came on. Before I even hooked up my Tech 2 to check codes, I knew what I'd find - sure enough, P0420 and P0430 catalyst efficiency codes for both banks! There's simply no way that those tiny "high-flow" cats have sufficient O2 storage capacity. Oh well - I'll just have the cat monitors "tuned out".
I have an appointment with Pat G on the 9th for a full dyno tune with wide-band. Hoping my truck is a beast after that!
12-22-2010, 12:06 PM
#2
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Good to hear!!!
I'm
Leaveing my stock cat back on also. It sounds great now headers should help
Does Ur exhaust have a cat before muffler and a rasonatior
I'm
Leaveing my stock cat back on also. It sounds great now headers should help
Does Ur exhaust have a cat before muffler and a rasonatior
Installed a set of 1 7/8" ARH headers and catted Y-pipe on my 2008 Seirra Denali this week, and here are the details . . .
First - I would have never guessed in a million years just how "rowdy" my exhaust would sound with headers! At certain RPMs and throttle openings, all he!! breaks loose (a raucous, bellowing roar is my best description) at the rear of my truck, LOL! I still have a completely stock cat-back, mind you! I'm very glad that I had not removed the resonator, as I had been considering!
That said, during normal cruise, it sounds very near stock, just a tick louder. VERY nice. Also interesting that during part throttle acceleration, say approx 1/4 to 1/3 throttle - at each upshift, when the ECM cuts fuel delivery during the upshift, there's a quite noticeable "back-rap" sound. Overall I must say that I'm pleased with the sound, though. Definitely NO cruise resonation or any other such nonsense.
As far as the performance difference, it's hard to say at this point. I suppose that the exhaust note difference makes the performance difference difficult to determine. Seems that it MAY have lost a bit of low-RPM torque, though at higher RPMs I believe there may be some improvement. To be expected, I suppose, with 1 7/8" primary tubes on a 378" engine. Admittedly, the traffic and weather yesterday afternoon and this morning have not yet allowed me to make any heavy or full throttle runs through the gears yet.
The installation was an absolute breeze. If ARH would have sent the correct Y-pipe to start with, we'd have been done in less than 3 hours. No fitment issues, excepting that the #1 and #3 tubes are EXTREMELY close to the steering shaft. Had to use a cutoff wheel to remove the protruding threads of the upper pinch bolt and part of the pinch bolt spring-steel flange nut. The battery cable to the starter solenoid had to be relocated forward. The oxygen sensor wiring all reached fine with no extensions necessary. My only fitment gripes have to do with the steering shaft intermediate shaft interference, and that the Y-pipe hangs down below the transmission crossmember just a touch.
One more BIG gripe though - on the way to the shop this morning my CEL came on. Before I even hooked up my Tech 2 to check codes, I knew what I'd find - sure enough, P0420 and P0430 catalyst efficiency codes for both banks! There's simply no way that those tiny "high-flow" cats have sufficient O2 storage capacity. Oh well - I'll just have the cat monitors "tuned out".
I have an appointment with Pat G on the 9th for a full dyno tune with wide-band. Hoping my truck is a beast after that!
First - I would have never guessed in a million years just how "rowdy" my exhaust would sound with headers! At certain RPMs and throttle openings, all he!! breaks loose (a raucous, bellowing roar is my best description) at the rear of my truck, LOL! I still have a completely stock cat-back, mind you! I'm very glad that I had not removed the resonator, as I had been considering!
That said, during normal cruise, it sounds very near stock, just a tick louder. VERY nice. Also interesting that during part throttle acceleration, say approx 1/4 to 1/3 throttle - at each upshift, when the ECM cuts fuel delivery during the upshift, there's a quite noticeable "back-rap" sound. Overall I must say that I'm pleased with the sound, though. Definitely NO cruise resonation or any other such nonsense.
As far as the performance difference, it's hard to say at this point. I suppose that the exhaust note difference makes the performance difference difficult to determine. Seems that it MAY have lost a bit of low-RPM torque, though at higher RPMs I believe there may be some improvement. To be expected, I suppose, with 1 7/8" primary tubes on a 378" engine. Admittedly, the traffic and weather yesterday afternoon and this morning have not yet allowed me to make any heavy or full throttle runs through the gears yet.
The installation was an absolute breeze. If ARH would have sent the correct Y-pipe to start with, we'd have been done in less than 3 hours. No fitment issues, excepting that the #1 and #3 tubes are EXTREMELY close to the steering shaft. Had to use a cutoff wheel to remove the protruding threads of the upper pinch bolt and part of the pinch bolt spring-steel flange nut. The battery cable to the starter solenoid had to be relocated forward. The oxygen sensor wiring all reached fine with no extensions necessary. My only fitment gripes have to do with the steering shaft intermediate shaft interference, and that the Y-pipe hangs down below the transmission crossmember just a touch.
One more BIG gripe though - on the way to the shop this morning my CEL came on. Before I even hooked up my Tech 2 to check codes, I knew what I'd find - sure enough, P0420 and P0430 catalyst efficiency codes for both banks! There's simply no way that those tiny "high-flow" cats have sufficient O2 storage capacity. Oh well - I'll just have the cat monitors "tuned out".
I have an appointment with Pat G on the 9th for a full dyno tune with wide-band. Hoping my truck is a beast after that!
12-22-2010, 03:50 PM
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I tossed up buying ARH, but couldn't bring myself to spend the $1500 when LPP are $1000 less for the same performance gain. I should be getting mine tomorrow. Can't wait!
12-22-2010, 07:31 PM
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Congrats on the install. But after hearing all your issues, it makes me happy I went the "cheapo" route with my Pacesetters. The only issue I had was getting the Y pipe to work right... but that is because I had already modified it to work on my 08. I have zero issue with steering shaft clearance. There is a 1/2" gap between the headers and the frame at the closest spot. I don't think paying half the price and having half the issues was such a bad deal now, regardless of the 1 3/4 primary size.
12-23-2010, 03:04 AM
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Great write up. I heard that pace setters came out with some kick *** LT's for the TBSS but now is the first time hearing about them on NNBS's. Well i guess i have to do some research now. Anyways good to hear your happy with the install and the headers.