Yes, the 325/660 is a front tire also. I just meant to say if running the 660 I'd opt for the 325 over the 305 as it will handle a greater load.

Fadi, the biggest issue you will run into with running the 645/680s is ice mode. The diameter disparity between 245/645 and 305/680 is huge with the rear being 1.5" larger than the front. The stock street TT ABS unit on the other hand is programmed for a slightly smaller rear tire. Be very cautious when testing this and expect to loose brakes in bumpy areas of the track or when applying brakes hard and fast. Don't be surprised to get a rock hard pedal with no braking action and when you get it you will have to fully release and reapply in order to restore any braking.

This past weekend at the track, for time trials, a friend tried a set of Yoko 245/645 and 280/680 Cup slicks on his street 6GT3. These have the same diameters as the set up you want to run. Long story short, he ended up getting ice mode pretty bad resulting in a significant high speed off. Luckily no damage to the car besides a ripped off splitter.

When I ran 25.5/26.4 diameter tires with the stock ABS unit, I was on the very edge of getting into ice mode and had to back off in certain areas as a result of it. When I switched to the Cup ABS unit, all issues went away as the Cup unit is programmed for slicks and a +1" larger rear tire. I think the ABS will be the biggest challenge you will encounter with the 645/680s. The stock ABS unit is marginal to begin with and it's only aggravated when running slicks especially with grossly different tire diameters. Be careful and good luck.

Now it's clear.... wow....scary! I'm not going to try the 680s anymore, will list them for sale tonight, didnt know about the ice effect, thank you so much for this valuable info

Ordering 325/660/18 problem is the fronts are a bit used but guess even so it is better than running the taller ones

If you hear about somebody selling a cup ABS please let me know

I think that's a smart move Fadi. I would start with a full fresh set but if it's the fronts that are used you'll be ok. Take it easy until you scrub in the rears.

Keep an eye out for the Cup ABS unit as they come up for sale occasionally. Keep checkin the Rennlist Cup car forum as they normally pop up there. Just last month I bought another Cup unit to have on the shelf as a spare. The ABS units rarely ever go bad but I wanted a spare just in case. They are worth their weight in gold as they are no longer made. The braking ability you get with the Cup ABS is astonishing, really a game changer. It's one of the best upgrades I ever did to the car from a performance standpoint. When they come up for sale they usually sell the very same day. You can expect to pay $4-5K for one. Make sure you get one with "Diagnosestand A02" programming as that was the last version. It's clearly marked on the front of the ABS unit and also comes up when you scan it with PST2/PIWIS.

[url=https://flic.kr/p/zZkB7H]https://c2.staticflickr.com/1/627/22...ec5f2c05_c.jpg

Thanks John, have ordered already the 325/660-18, seems there is new composition DHC but keeping also the old DH, went with the DHC as the vendor recommended

You will be fine with 660 or 640. I've run both, and had several discussion about them with Pirelli reps. The only time to give it a second thought is on banked tracks. Pirelli's are tough and you aren't likely to overload them with a street turbo. Never heard of the DHC compound though.

June of 2017?

Not sure if there's a better thread for these but here are a few videos from 09DEC17 at The Ridge in Shelton, WA. I have never been to this track before and was only my second "real" (not counting a small paved oval track I ran a handful of times) track day in this, or any, car. Probably a bit sloppy from time to time and I go off in one the second video and almost go off another time trying to squeeze a few extra mph out of the front straight! hilarious Highest speed I saw there was 150 mph. It was cold but it was a blast and got to meet and hang out with some cool people.



This last one is just a short clip I had someone record for me using my phone since I didn't have any external recordings of my car post exhaust install.
http://webm.land/media/45TL.webm

I've got a few complaints after my first track day in my new (to me) 996 turbo.

It's got RUF springs and B8/Koni shocks with 245/18 and 315/18 Falken RT615k+'s. Brakes are Hawk Black front pads and ??? rears with SRF fluid. It has ~2.4 degrees camber in the front and about 1.3 degrees rear. Stock powertrain.

Complaints:
- Brake effort vs stopping power was HIGH. I could get it to get into ABS but man did it take way more force than felt right. The session I was able to threshold brake, I also boiled my fluid in 6 hot laps.
- It feels HEAVY, but also a bit nervous in transition. It has an H&R rear bar, currently on the softest setting. I'd like to be able to change direction at light throttle without worrying about weight transfer causing oversteer. Setup recommendations to help with that?
- Jeez this car generates a lot of heat!!! Anything I can do to help lower IAT's without changing intercoolers?

You guys might remember me from way back. I ran and won all the HPDEs and I had a great time, moved into instructing and now I race. But I switched over to something more economical and fun. Porsche 944. I spend $10K per year on racing, and that gets a lot of seat time and I win sometimes, which is awesome.

This car cost me $11K to buy and build, incliding the AIM DASH.


https://cimg6.ibsrv.net/gimg/www.6sp...1c2b3b722.jpeg
https://cimg7.ibsrv.net/gimg/www.6sp...dd397c22d.jpeg
https://cimg3.ibsrv.net/gimg/www.6sp...370a07f71.jpeg

Next year I’m moving to this monster late model stock car, set up for road racing, another $11K beauty:


https://cimg7.ibsrv.net/gimg/www.6sp...279d137fa.jpeg
https://cimg9.ibsrv.net/gimg/www.6sp...5e4fc7550.jpeg
https://cimg3.ibsrv.net/gimg/www.6sp...9d0d24ba4.jpeg
https://cimg6.ibsrv.net/gimg/www.6sp...562795cd5.jpeg

Looks like a lot of fun with a reasonable budget! Videos?

Buddy, You can see some of the video from last weekend here: https://www.youtube.com/channel/UCeb...jehshf3IyYwQQ/

This year I won the 944Cup National Championship in SP1 (September 18) and I just won the NASA ST6 Race last weekend, even down by some 100# and having been hit by another competitor in ST6 qualifying.

Fun FUN FUN!!!

What kind of HANS devices are you all using?