Lonestar13

I have a 2013 GS, 3LT, A6. The warranty has expired, and now I want more HP. I am seriously considering one of 21st Century Muscle Car's performance packages. No matter what I do, I want somebody that can properly tune the car no matter what mods I make.

I have been looking at the Edlebrock package without the headers or exhaust. I know that the performance will not be the same without the headers and exhaust, but for a car that is not a daily driver, and not tracked, how significant will the difference be?

EvanZR1

Matt at 21st is a great tuner, would definitely trust one of their packages. As you've seen, 21st prefers the PD (positive displacement) top mount style blowers, which make better low end torque but not as much peak HP. There are other good options in town for centri style blowers (Quality Motorsports in Lewisville does A&A, there's also TrueStreet in McKinney). It really depends on what your goals are. If you just want a fun street car that's reliable, then you can't go wrong with the package from 21st. If you're looking at eventually doing BIG HP (700-1000HP or more), then the Edelbrock probably isn't the way to go.

I can tell you that just the bump you get from the Edelbrock will put a big smile on your face, and should keep you happy for several years if you've stayed stock for this long. Be careful who you hang out with though, as Dallas has a lot of crazy HP cars running around and you'll still feel under-powered if you happen to face off with one of them.

LSX228R

I have the a&a supercharger kit and its been perfect for over a year now. Honestly, the stock manifolds and exhaust wont hold you back much. The biggest difference is the sound. The car will sound a lot meaner with headers. My advise is to do it all at once so you don't pay for two tunes like I did. As you can see below, the biggest gain is in the mid range.

Stock manifolds and cats vs arh 1 7/8 long tubes w/no cats

CI GS

21CMC tuned this car:
https://www.corvetteforum.com/forums...-hearbeat.html
I think they know what they’re doing.
I haven’t come across another C6 that has run a 9 with a stock long block (except cam), stock gearing, stock converter, no meth, etc.

WA 2 FST

As Evan said above... I would absolutely trust 21CMC for a reliable upgrade in power, that will put a smile on your face, and they back their work.

They have worked on a number of vehicle for me: starting with a LPE Stage 2 twin turbo set up on my 2002 C5Z...a car I bought new, took to them two years later for the TT setup, and I still own today.

They also did an upgrade on a 2012 CTSV, tuned a LPE SC 2012 C6 (Edelbrock set up like you're looking at, only it also had ported heads, cam), and most recently did an install of a blower on my SRT Jeep. I don't still own all these cars, but did at one time, and I never had an issue with any of them.

21CMC has also done some routine maintenance for me, when I didn't have time to do it myself. John runs a great shop, and Matt is as trusted a tuner as you will find in our area. They listen to the customer, will offer suggestions, but will NOT oversell you on things you don't need to reach your desired goals.

98Pace

I had 21st do their 525hp cam package on my 08 and have been nothing but happy with their work. Matt did an amazing job of tuning my car, to the point where I sometimes forget it has a cam it behaves so well. I can still daily it if I choose. Their recommendations based on my goals were spot on and I have no regrets about the work I had done.

I would not hesitate to recommend them to anybody. Top notch shop!