I removed the upper plenum and gained 5whp back. The ported lower is still on. I'm just trying to find the time to change it. It's a bit time consuming and I don't have a inch/lbs torque wrench so I'll have to barrow one from a friend.

Its got to be your tuner. Are they doing a custom pro tune? My first tune with Fast intentions long tubes i made 316whp i only gained 5whp from my Untuned baseline and i barely picked up across the board. 3 weeks i scheduled another tune with a different person and come to find out I was running super lean from 2-3 and kinda rich across the board. He ended up fixing that problem and i picked up huge from 2-3 and gained 18whp at the end. For some of us we have great tuner close to us for some you have to travel. That guy in tampa made crazy numbers with ported lower and z1's upper. Hope you find a solution to your problem.

Thats some great numbers. Our dyno sheets don't differ to much. I make 300whp little sooner that you and make 4 more ft/tq. Great stuff

This^^. I've gained 12 hp between tuners before with no changes to my car.

I don't believe it's an issue with the tuner. I went to rob at topspeed Motorsports. I gained 15whp with his tune. He's a very reputable tuner that worked for Z1 for a long time before he left to start his own tuning company. He tuned my friends 370 that uses the same setup I use and gained 25whp ending at 325. My a/F ratios are perfect. Even my friend who owns a Dyno commented on how spot on it is. I'm just not sure if I should try to take it some where else and try to tune the car again.

hey sorry man, but but how much WHP did you think you were going to pick up? Those mods together would net you "maybe" 5-6 over stock. At least thats how it worked for me by differnece was in the mid range and throttle response. but to be at 305 WHP and not have headers is about right. Remember all these other people "including Z1) throwing dyno numbers around dont mean squate. Every dyno is different, IMO most places inflate numbers to make customer happy. ( 341 WHP NA 370 Sure)Dyno's tell you almost nothing other than your tune is safe cause you can get the car up to 120 MPH for tuning and not worry about crashing. You wanna see what your car really makes hit the track and take you 1/4 times and MPH with you curb weight and figure it out. If you happy with the way the car performs on the street then be happy, chasing dyno numbers will do nothing other than upset you casue no ones is the same.

BTW I have every bolt on and ECUTEK tuned by Seb and we all know how good he is and my dyno told me 314 "uncorrect". But thats just want a machine told me, I will compare to my track numbers last yeat of 13.5 at 105 MPH (3800 LBS) X sedan.

While I understand what your saying I'd like remind you I lost 7whp by just putting the plenum on. I installed the lower took the car for a run and was down another 5whp. When I reinstalled the stock plenum I gained 5whp. I understood I probably wouldn't make much, I just didn't expect to lose more power than I made by installing test pipes. I didn't expect to lose power period...

Any news on this?

Yes, I lost a lot of money and power. Z1 took their parts back but they wouldn't give me my cores back, so I had to go source new cores. Total cost between Dyno runs and used oem parts to prove I lost power $360. Total loss of power with the plenum and manifold was 10whp. Now I need to have my car retuned for the stock manifold setup. That will be another $300. Honestly the frustration of all of this has me seriously considering selling my car and moving on to something without a plastic clutch slave cylinder. Maybe it was a fluke that I lost power but how would you feel if you spent over $600 on parts that lost you 10whp. I would not recommend buying these two pieces.

My buddy installed ported lower by sync and lost 10whp 15ft tq, but wasnt tuned.

If you're looking for power stop wasting money on every bolt on in the, market. Just go forced induction. Bp makes a reasonable price kit

Ditto

Wow! You already have a license. Most retunes should be an hour or $100!!

I've got nothing to say on this though. I've paid for a few guys licenses and all made power by running the car and tuning, installing new within an hour and running again. Maybe they weren't port matched as a set and lips were formed.

CSC does suck!

Yeah the tune is good. I used a reputable tuner who has tuned many 370zs and GTRs with ecutek. I get the Bp kit and was really thinking of heading that direction but between this and watching a few friends seriously struggle with their CSC it's got me seriously considering going a different direction. I love my z but I'm beyond frustrate from this whole ordeal; losing my cores and having to source new ones really rubbed me the wrong way; also I live in Alabama and you don't make friends in the southeast z community by questioning Z1. That's soured me a lot to the commuity down here.

Did you have throttle bodies?