I want to make around 650whp on my g35 are sleeves necessary are a high risk. I could make more horsepower In The future but not know. Thanks for the comments

 

If you are planning to push more than 700-750 then sleeves are good, but up to there people get by with the HR or other quality head gaskets with good head bolts with seemingly no problems.

 

It was a popular idea in the early days of the VQ but has seen lots of failures due mostly due to improper installation.I know of several people making over 700rwhp without sleves...do a little research over at my350z.com our sister site.