(Originally posted this on one of the "other" forums, but felt it deserved a share here as well).

So after spending a couple weeks soul searching, trying to decide if I wanted to trade the 08 Imp SS w/ 97,000 on the clock or keep it until it falls apart, I decided on the latter. I figured if I was going to keep it I might as well make it as fun to drive as possible. Jumped on the web, ordered front and rear Don Rome STBs, an SS to replace the front bowtie, new floormats, a TransGo shift kit from TEP and most importantly an InTune device and a custom tune from Lew (06MonteSS here).

This review is specific to the tune. Haven't received the STBs yet, so stay tuned for those .

First and most importantly, beyond even the tune, Lew is an amazing guy to work with. His customer service is absolutely second to none.

The only performance mods on the car prior to the tune are a K&N intake, a front brake upgrade to the 2012+ 9C1 setup and the TransGo shift kit.

I got the InTune device and loaded the non-DoD "Diablo" 93 octane tune along with the firm TCM tune. I noticed immediately that my car didn't like the combination of the firm TCM tune and the shift kit. Shifted way too rough for my liking and I experienced a notable shudder while driving at highway speeds going uphill. Reverted that back to the stock TCM tune and made a note for Lew.

Drove the required 150 miles on the Diablo tune before datalogging.

Observations of Diablo tune (not custom):

• Car felt a little "rough"... it didn't idle as smoothly as stock
• RPMs were all over the place while driving. At 85 mph with cruise turned on while on a flat stretch of highway RPMs would wander by almost 200 up and down. Was terrified this was my torque converter going bad.
• Car was more potent. Throttle response was increased.
• Mileage dropped from a high of 23.9 on the highway with DoD to around 21 highway without DoD.
• Shifts were the same as stock since I couldn't use the firm tune, and of course wasn't going to touch the "hard" setting.
• Still experienced just a tiny amount of shudder on the highway when going uphill. Unsure of the cause.
• DoD shudder when slowing down and kicking from 4-8 cyl FINALLY eliminated! This was one of the main factors in deciding to get a tune.

After the 150 miles on the Diablo tune I emailed Lew my logfiles late on Saturday night. Woke up Sunday morning to a custom tune in my inbox! Immediately ran out like a kid at Christmas and loaded the tune onto the car.

Observations:

• Idles smooth as glass now
• Throttle response further increased, almost instantaneous now.
• More torque and power available than the Diablo tune. Accidentally left some rubber behind at a few lights . Passing on hills on the interstate that would've triggered a DoD-off shudder and downshift before are done with ease now. The car rarely drops out of O/D when cruising, even on hilly interstates at 85mph.
• No sign of shudder at any speed or under any conditions.
• Mileage increased to 24.1 without DoD.
• Shifts are perfect now. Just a little firmer than they were with the shift kit and stock programming. It downshifts quickly, upshifts smoothly with a satisfying snap when I'm on the throttle, but still comfortable around town.

After 150 miles on Lew's custom tune, he further refined it through another datalog, though I'm not really sure what all he changed on the second one.

My next goals for the car are a catback exhaust so it sounds as nice as it performs then a performance TEP transmission rebuild (later, hopefully). The original transmission currently has 97,000 miles on it. Has been to the dealer once to get the 1-2 and 2-3 solenoids replaced under warranty. Shifted ok before the shift kit and tune, but was typical 4T65E-HD sloppy and unrefined. After the TransGo and Lew's tune it actually feels like a sporty transmission.

In my humble shadetree mechanic opinion, a Lew tune should be the very first performance dollars spent on an LS4 car. I wish I would've done this the day after I bought the car.

For those interested you can contact him on most any LS4 related forum or go to his website here:
DiabLew Tune - Custom Tuning for GM Vehicles - DiabloSport inTune, Trinity, Predator Custom Tuning by 06MonteSS

And no, I'm not related to Lew, I don't work for him, I've never even met him lol. Just wanted to share my experience since it was forum posts that made me decide to take the plunge to begin with. If you're considering it...DO IT!

 

This could have been my review of Lew as well, if I had written one. Very nice and easy to work with kind of guy. As a cheaper alternative to an actual dyno tune, I would recommend Lew every time. Nice post.

 

Lew was great to work with!


Diablo was the ******* suck....

 

Nice! Glad to hear it man! And Thank you for the kind words, I really appreciate it - from everyone!

www.diablewtune.com

as to what I change on the subsequent tune updates and datalogs, it's to get your fueling/fuel trims dialed in to where they should be... that's another variable that helps with throttle response and acceleration...

Thank you!