Well after several months of research trying to find an exhaust louder than stock but mellow enough for me not to go nuts I found it!

At start up and idle it is almost identical in sound to stock with just a touch of a sport sound that tells you it is not stock.

Cruising at lower RPM's is great with a mellow sporty sound that will not drive you crazy. This was the most important part in my search and I can honestly say it meets it .

If you want a more aggressive sound all you have to do is Step on It! and you will get the sound.

So all I can say is I found what I was looking for and I really appreciate the great service and response I received from John @ Speedtech.

And believe me I had several questions and John was always happy to respond.

 

I guess my question is related to the size of the piping....at what hp threshold or turbo size are you more or less required to jump up to the 70 mm piping to reduce the backpressure and maximize performance? Most tuners push their clients towards the 70mm pipe.

From what I've heard, SpeedTech it very responsive to customers' questions and issues.

 

I also recently installed the speedtech 60 and am very happy with it. Perfect sound and a power improvement. Good service too.

 

Glad to hear you two are enjoying the exhausts! Thanks again for the orders and the positive comments, I appreciate it.

Chuck, I am not certain of the exact level that larger piping is required, but I will share the following: My fastest 1/4 mile time with K24/18G's was with the 60mm system. When I went to the 70mm, I expected to break my personal best, but was unable to do so. I was within hundreths, so basically identical performance, but the fact remains that my fastest time was with the 60mm. Based on this data, I feel that up to 700 HP the 60mm is fine. Beyond 700 HP, the larger piping is probably required to optimize the turbos performance. The larger piping adds volume, though, so it would not be out of the question for a larger build to run a 60mm exhaust, if the goal was a quieter system. IMHO, there would still be adequate performance being delivered with a high flow 60mm system, to result in an exciting ride, even on a larger GT30 type set-up...

 

John: Thanx for the explanation...I realize that some tuners strongly suggest the 70 mm piping because it allows the car owner to keep bumping up the HP (as so often happens once the bug bites), and the larger piping would not require the reinvestment in a new system. I'm with you on the performance. I run 60mm pipes with 100 cell cats, and the performance has been stellar....but I have no aspirations to take it over 600....so the additional costs for a 70 mm system are unwarranted. I guess the remaining question I might have would be....if you go to bigger turbos or the hybrids....is there any inhibiting factor there when using 60mm? Your timed runs would suggest not...and I'm sure you weren't running stock turbos.

Thanx again for the explanation. I believe that it's important for the folks who are planning on performance upgrades to discuss these issues with their tuners and be aware that bigger is not always better....depending upon what limitations you have set for yourself...and what your VISA can handle. So many folks don't know what question to ask, or how the final objective fits into the equation, ....and can end up with a recommended solution that may not be necessary.

 

Chuck,

My track runs were with K24/18G turbos and race fuel. On the dyno there is a slight HP penalty for using the 60mm vs. 70mm. In real world performance, it appears the difference is not significant based on my track data and seat of the pants. Both systems perform well on the street and track. The 70mm has a throatier more aggressive sound, which sounds very good and the 60mm is higher piched, not as loud and also sounds very good. IMO, it's more a matter of sound preference until later stages, where a larger exhaust is probably required if you wish to maximize your mods. That said, our even larger piping, 3" X-cellerator crossflow exhaust is quieter than both of our conventional systems, flows extremely well and offers some options not available with the conventional systems. The 100 cell cats on the X-cellerator crossflow allow the turbos to spool quicker and you can hear them whistle, which is cool sounding, but it is also a slightly more expensive system. As you pointed out, it's all about choices and goals...

 

John: It's really refreshing to hear the straight story without any embellishments or venues. I sincerely thank you for your up front assessment and honesty in explaining the differences between the two systems. Given your explanation, it would appear that for us guys/gals who really have no aspirations for big horses or shaving .04 off our quarter mile times....would have no real need for the larger pipes.

You're right about hearing the turbos spool and whine....I get that with the EP system that uses the 60 mm pipes and it's a hoot to hear. I also routinely run at 1.2 bar.

Thanks again for the straight story.

 

I too appreciate the insight and explanation. These forums sure do help the guys who enjoy their cars but have an average knowledge base. Thanks