How much of a gain can I expect from SLP runners and a ported plenum with an LT1 cam. Also what is needed to install the LT1 cam. This is on a 1990 TPI 305 with full exhaust, air foil, k&n and performance ignition.

 

Don't waste your money on the runners. Unless you do something with the manifold, you won't notice much at all (5-10hp). Invest in a Crane compu cam such as CRN-104225 and you will be able to feel a noticeable difference in power. If you have a 3:42/3:73 gear, you can order the CRN-104224 crane cam. These are very nice cams made to work with your ECM and do not require any ECM reprogramming at all. These cams work best with headers but not neccessary to have them.....I have used the crn-104224 cam in the past and it works very well.....available thru Summit for $270...................................

 

As per Lingenfelter, go with the best set of heads you can buy. If it comes down to a roller cam or heads, go with the heads. Also go with good roller rockers. I would recommend AFR heads with Crane Gold roller rockers.