L31MaxExpress
I'm Awesome
Not trying to change your mind, but for the sake of others on here. Make no mistake, I am a tri-y or atleast a long tube kind of guy, however I have run a few sets of shorties on numerous vehicle makes and models. Shorties still offer a signifigant power increase for those that are bound by emissions. I have had 2 different Nissan VQ V6 engines that I replaced the OE tubular manifolds with shorties on. Both gained power that was easily noticed. The extremely short primary, dump collector design sucked on the OEM manifolds and the shorties equal length merge collector combined with the longer primaries added considerable torque to them. I did not even spend $150 a pair on the Nissan headers. Both were "Used" but merely open box items from Amazon. While they call then "shorty" the VQ headers are more like a mid length.As a repair, yes. As a performance upgrade, no.
I'm not wasting my time to remove functioning manifolds for shortys. My opinion of course.
I have had experience with shorties on the 97 van, the 80 Corvette, the 03 4.7 Dakota, the 07 G35 Sedan and the 2011 Pathfinder 4.0L as well as the shorties from the 97 van that went on my brothers 99 Suburban.
Not a single one was a dissapointment before and after. They all smoothed out the torque curve with gains at peak and even bigger gains in other areas of the power curve. There were places the equal length shorties picked up ~25 ft/lbs on the VQ35HR. The Pathfinder runs more smoothly, has noticeably more get up and go and holds speed with less throttle and less downshifting towing a ~4,000 lbs trailer. The shorties are definitely better designed than the OEM, get the engine to fit in the chassis and hope some exhaust gets out method factory engineers use.
What came off The G35
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What went on
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What came off the Pathfinder
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What went on it
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These replaced the literal log manifolds on the Dakotas 4.7L. That 03 4.7 had the HO cams and 2008+ intake manifold on it to start with and got a best of 21.5 mpg highway. First trip post headers it managed 24 mpg cruising 75-80 mph most of it. It was definitely choked by the stock manifolds. That Dakota also had somewhat of a hack method of tuning as well. It was an early 03 NGC1 controller that nobody supports tuning wise. I had a Superchips I had previously run on my Ram before I bought the SCT tuner package for it. I flashed the Superchips into it and had a PSC1-003 signal adjuster on the MAP sensor. By manipulating the MAP sensor voltage to the PCM I was able to dial in the fueling to compensate for the airflow changes. At WOT the truck thought the manifold was at 105 KPA for example. For something the manufacturer claimed one could not add additional fuel with it worked exceptionally well doing. Post headers I had to give the PSC1 a nearly 5% increase in MAP voltage across the whole map to keep it from running lean.
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That Dakota was a fun little truck. Little V8 with a 3.55 gear and still hard to get it to hook up. My brother had a 98 R/T with the 360 and 3.92 gear and I wore him out with that little 4.7 he could get a door length on me until 30 mph then I left him far behind. Then he bought a 2013 Avenger 3.6L put a large cone filter in the stock airbox and a magnaflow muffler, deleted the resonator and wore me out until it smoked the transmission for the 3rd time.
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