The car is a 93 Porsche 968, front engine, rear transaxle with 5 sp Turbo S LS transaxle. Final drive in fifth at 6200 rpm is 175 Mph. It is getting an LS1 with 243 heads and it will be dry sumped. It will not be the DD but has to have manners and must meet emissions. So in that light I'm going to forged pistons and rods and, rod bolts, main caps and good balancing. The cam is the 02 ZO6 with hollow intakes and sodium filled exhaust and I'm wondering if the yellows are OK, or should it be 918,s or dual patriots for example. The test for the car will be Mosport (very fast) and has potential for missed shifts so I'm thinking the top end has to handle big revs. Based on everything I've read on the subject it seems that a high closing pressure and progressive clamping is the best way to keep valve float under control. Is this a reasonable approach or, and what springs would work best in this scenario.

 

PAC Racing 1518's with titanium retainers and machined valve locks.

 

That looks like a great package. Thanks.