I recently got 3 or 4 estimates from local metal polishers to get my spare plenum and TB's polished. All of them after seeing the work gave me an estimate of between $400-$450. I ended up shipping it to SGP racing which quoted me $400. One of the reasons I sent it to SGP is that their polisher has done Z plenums in the past and the locals here had never done one..Hope it helps...
: How much are people paying to have their intake plenums polished?