Range Rover P38 2.5dse 1999 Diesel (psi Powerbox Chip)

Im Thinking Of Puting A Psi Power Box Chip Into My Range Rover 2.5dse P38 Diesel 1999. I Was Just Thinking, The Chip Wouldnt Blow The Head Would It? The Range Rover Has 93,000 On It. Are They Any Downsides To This Chip. Also Does Any1 Know Where I Can Get 1 In Leeds, Or By Leeds. For A Reasonable Price. Thanks