i sold my edelbrock base and slp sia. runners and ported plenum to a buddy of mine for his '91 Z 355tpi/5spd it actually slowed down ! he went from 12.98 to 13.1 and lost a 1mph...what gives! my car was running 12.8-9's with a ported base ,slp runners and 52mm tb on radials..mines also an auto with a stall and 3.73's compared to his 3.55's, then again my car is about 150 lb's heavier too..? ..strange eeh?

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87GTA 355TPI,A4 shooting
for low 12'

 

The problem is the SLP Runners, not the base. THe ports are inconsistently shaped, plus they are a poor design. With the stock runners and ported edelbrock base, the time will improve by .2 and the ride will be much better. I know mine did.

 

i didnt have a problem when i had them on my car,,but at the time i had my ported stock base still.. so that could maybe change things ..who knows

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87GTA 355TPI,A4 shooting
for low 12'