Im posting this because when i needed the info i could not find any on this matter.
so i did a mild gsr build. gsr block with p30 pistons(stock bore). the head was all stock just replaced valve springs and retainers NO pnp. bolt ons were sk2 cams, intake manifold, pro fab header, 2.5 exhaust.
I had this tuned by Todd at church automotive. Most people i asked on here and other websites under estimated this set up, and said it would only put down 170-190 190 being lucky.... well mine put down 211hp and 150Tq.
i have the graph just dont know how to post pictures on here..
I hope some1 looking to use p30 pistons or looking to do a mild gsr build will find this info usefull ........

 

yeah but the dyno they use at churches reads a bit higher then most tuners who use dyno jet. just be happy Todd tuned your car.

 

Todd tunns my car every time there he knows his **** look at his lsvtec he has i believe it is 280hp! the last motor i had him tune was a gsr block jdm pistons about the same comp. as your p30's,gsr head no pnp either sk2 pro1 cams/vt, sk2 pro ser i.m, hytech rep. bigtube, 2.5 catback and 3'' cai, he tuned it at 216hp and 150tq! im about to slap a jrsc to this mix and have him retune this monster lol.

 

yes i've heard that theyre dyno does read a bit higher, but there are a lot of arguments about wich dyno is more accurate. some think dyno jet is better ans some like dyno pack. i dont know wich is better, but i also think the difference would be to drastick

 

yeah i saw that 280hp to the wheels and that is his dd, must be nice..i think i could have made a lil bit more power if i had a better header and intake, i've got a pro fab header and 1 of those cf intakes from password jdm

 

yeah my LS vtec with ITRs and buddy club Spec 3s and S2 intake made 195 WHP with a DC sports header...lol

 

None of them are "better" they are tuning tools only, not the be-all-end-all god of HP determinating. Your car may only put down 185whp on a dynojet but what really matters is how happy you are with how the car runs and performs.