Originally Posted by SamboTT@ByDesign

The factory billet .2 TTS units are about the same size. But it’s not always about size. Just like anything even complete engine design has a lot to do with performance more than size. Often times as you stick a larger compressor there, the efficiency actually goes down. Your compressing more air, creating more heat and you’re removing more material from inside the compressor cover which has function. That’s why we worked with TiAL for a long time to get here. Our TiAL 68mm has always been up top in VTG performance as one of the top offerings and has a great track record. There are some cars that have highly developed tunes and run really fast with the 68. In those cases it’s not always worth upgrading to this next level but it’s hard to continue pushing a certain system and platform more and more, at some point you have to stop. The idea here was to make a little more power with a little less back pressure and effort, mission accomplished.

Originally Posted by 2018911TTS

I get to drive 2 cars and make direct comparisons between them. My daughter's 2017 TT the stage 4 set up with the Tial 68 mm's from @SamboTT@ByDesign versus my 2018 TTS with Sam's new stage 5 set up. My daughter's car is set on one of Sam's milder Stage 4 tunes and is around a 9.6/9.7 sec 1/4 mile car with a best of a 1.42 sec 60 foot and 145 mph with the Nitto rear and Toyo front tire combination. She says that is fast enough and that roaring down the 1/4 at 1.45 mph requires enough attention from her that she's not interested in dialing it up. The car could probably be pushed to go 9.5s @ 147 mph but for now she's fine with where it is at and that is probably better for long term durability with the stock ,motor and pdk.

My 2018 TTS with the Stage 5 is not only more powerful but to me feels more controllable because the power comes in ever so smoothly. Running 9.3s @149 mph I feel like there isn't much that could beat me on the street. However, when the car ran 9.6s there probably wasn't anything back then that could beat me - except maybe a Mclaren 720 or 765LT from a roll.

With the stage 5 you definitely pick up power over a stage 4 for any equivalent level of tuning and also better drivability IMO..

We love to drag race competitively and the Red List series is one of our favorites. However, that series requires you to make 12 full 1/4 mile passes in less than 4 hours. What usually ends up happening is that some car blows up and oils down the track which requires an hour to an hour and a half clean up. So that means having to make several back to back passes in order to hit your quota of 12 runs before the cut off time. So you might be doing 12 passes in 2 hours.

The August Red List events can push ambient temps of close to 110 degrees F with DAs well over 6000 feet. Doing repeated back to back passes with no cool down whatsoever is an endurance test for any car. GTRs and Demons are literally blowing up on a regular basis under these conditions.

Sam has my car set up on the stage 5 with a relatively mild tune where it is running 9.3s with a 1.38 60 foot time. That being said. under 110 degree ambient temp conditions with back to back passes the question arises as to how long a stock bottom end and pdk will last. If you blow your motor or trans the core charges can be pretty high. So that's why I decided to go with the upgrades on a proactive basis. Those upgrades will also leave me in a good position should NHRA change their rules and allow quicker runs without a 12 point cage in which case I would be able to switch the Sam's XR set up.

Additionally they allow me, with more peace of mind, to try a more aggressive stage 5 tune and maybe run 9.2s at 150 mph.

Most people don't go to the track as often as I do so it's more likely that a stage 5 set up won't risk hurting the motor or pdk as much as for someone like myself.

Everyone uses their cars differently.

However, I will say the stage 5 has enough advantages over the stage 4 that for someone like myself its been very happy transition. My daughter on the other hand is perfectly content with the stage 4 on her TT and set on a mild tune.

Originally Posted by onfireTTS

What is the 60 to 130mph time on your Stage 4 and Stage 5 ? Would be an interesting comparison metric.