When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Yah I talked to Tony recently before buying my 5/16" isothermal spacer. He told me that the 1/2" spacer produced more PEAK HP, but the 5/16" produced more area under the curve, which meant a more linear power gain. The latter is what I wanted, so I went with the 5/16". I got my kit from Performance Nissan. Andy and Kenny were pretty cool to talk to and I would recommend this place.
The 1/2 spacer makes more peak torque than the 5/16 spacer.
The 5/16 spacer makes more torque in the low and mid range.
So your decision is where do you want more punch?