Decompression plates are good to about 450whp although before you get there you'll reach other bottlenecks ie. pistons/rods. I think the reason most people have had problems with them is because they didn't do a complete install. You have to fully clean the block and head of any oil or coolant before reassembling them or your setting the gaskets up for failure. Either that or for the most part, people have been using the Alpine Decomp plate and maybe that's a piece of crap. When I used the Alpine one, I was leaking oil like crazy - but I also did a half-ass install. Once I got to Korea I had them put on a new one and now I'm running 300whp daily with no issues what so ever. Just my 2 cents.

 

HEY NOW you already have the pistons it isnt much more work to get the pistons in than doing a decompression plate. As long as they are stock bore you can just lightly hone the cyl walls with a ball hone and a hand drill. dont spin it to fast as you want to try and achive a 45 or 60 deg angle i cant remember chiltons manual has it in it. once thats done installing is easy and much safer than decompression plate. I just know what you have gone through and it dose get troubling some times but it will be worth it if you ever blow a headgasket with the decompression plate as it will save you from having to rip it apart again. JMO though. anyway good luck whichever way you decide.

 

depends how old your car?
before the decompression was installed there were several checks and maintenance that was completed.

- engine block, cylinder head, engine was cleaned and reconditioned.
- apparently there was so much oil residue that needed to cleaned out
- check engine condition
- replace all the gaskets, timing belts

Get a professional to get the work done.