blew my last motor at 80000 miles got new long block from absolute german in seattle has 96000 miles with stock turbo.i swapped over my apr st 3+ onto the new block. for the first month the engine ran fine and held boost at 25 to 27 psi. all the sudden the engine started running ****ty, misfiring mostly, would bearly hold and idle. changed maf sensor, the power supply for the coil packs (don't know the name) replaced stark plugs. now it idles and runs fine and holds boost up to 10 psi but begins miss firing anywhere above it. i'm runing a manual boost controller, i tried to turn it down to see if it would make a difference but it didn't. next thought is coil packs. but before i spend the money to replace them i was wondering if anyone has any idea or has seen this symtom before. any info would be nice thank you

Explain the heat range. Is that the avg temp your turbo is running? How do you figure out heat range. I'm starting to have the same problem. When I get up to about 5k rpm, it starts to bog and slow down. I'm running a 2871R @ 15psi. Also, anyone familiar with wether or not I could be getting away with more boost?

the temp the plug tip retains to burn off deposits.
IMO ... a 6 plug is too hot a plug for your bigger turbo set up.

to ignite the mixture. A stock setup would require a much different plug heat range than my car which runs 29lbs boost with peak at 33lbs.
Does that help?
Rod

Ok so on a bigger turbo you run a cooler plug? IE Go with 7's?

well not the problem at all. it was a whole different route. after completely determining that it was an ignition problem, we took a better look at the plugs and my buddy's technician found carbon mapping on the plugs, so after replacing the coil boots and plugs she's back up to boost again. now i'm going to hit a dyno on friday to see how much this setup can really produce. wish me luck that i don't blow this engine too. ps; stock plugs are the only plugs that have always worked the best!