Just installed a set of granatelli coil packs on my truck. My setup has a whipple supercharger/39lb cobra injectors/jba headers/magnaflow exhaust/SCT custom tuning. Initially, I was disappointed with the dyno numbers after the install. Granatelli advertizes about 10-15horsepower increase on N/A vehicles and up to around 20hp on Supercharged vehicles. I only got about 7-8rwhp increase with about 8rwtq increase. When I saw those numbers my heart kinda sank a bit. BUT...when I looked closer I reached those numbers about 600-700rpms sooner across the band. That kinda made me feel better. When I took the truck out for a spin I had a grin on my face (not a full on smile...but a grin). I definitely felt a better throttle response. So, my conclusion to this product would be get it (IF you can find a good price). I would not pay for list on this product to get that kind of result. I believe it lists for about $499-599. I got mine at lethalperformance.com for $379 shipped (this is with 5% off for holiday sale that they are having). Probably the limit I would pay for what I got out of it. I'm hoping it will payoff when I upgrade my supercharger to 10 lbs of boost from 8 lbs. Hope this helps anybody who's considering this product. Also, I did find a post out there that someone had problems with these coils at about 5000 miles. I'll see what happens with mine. I saw this post after I already had it installed. Wish me luck.

 

Good to hear your results are positive¡¡¡¡ I have my coil packs on order for a while now, but it seems granatelli takes a long time to process orders. How long did it take for you to get them?

 

Probably one of the few success (kinda) stories with those things. Several people that I know have had nothing but problems after installing them. Think Neal had a set and they never worked either. There is another company that makes high-output coils now and in their setup you have to reverse the polarity on the connectors to the vehicle harness before hooking up the coil packs. Is it the same with the G.M. coils?

 

I ordered mine from lethal and it took about a week. They had it shipped directly from Granatelli. I think mine was pretty quick because I reside in Southern Cali.

 

the gran, accells, and msd are made by microtech. I have a set of the grans and a set of accells coming. I am going to test both to see what happens. The issue people are having is the RF interferance from the new coils. Mostly due to pulling off all the RF reduction crap anyway

 

I have a set on my truck that I put on when i installed my super charger, so far no problems. I bought mine from TP and got them in 2 days. I bought them so when I up my boost to 10PSI it will help keep the spark from being blown out.

 

I had not heard that this was a problem with the factory COPs.
Lots of guys make big power with the factory coilpacks at higher boost pressures than that.
Are your plugs gapped correctly?

 

I did not start having blow out until I was pushing 16psi and gapped at 35. With the GMS packs I am gapped at 35 and hitting 25psi