Normally Aspirated, mid to high compression ratios at 12.5 * 13.5 * 14 (Max compression) - Pistons are good for 100 shot of Nitrous - milled inside for minimum weight but still retaining strength - if you don't see what you need, we can custom make for you - reach out at sales@traumpistons.com or WhatsApp (Chat only) +1 (424) 448-2875